Sustainability and ecology scenarios

Digital Task Water Footprint Scenario Calculator Estimate a supplied water footprint for repeated digital tasks from water per task and task count. Books Versus E-Books Emission Scenario Calculator Compare supplied production and use emissions for paper books and e-books. Car Versus Bicycle Trip Emission Calculator Compare supplied trip emissions for a car and a bicycle over repeated trips. Logistic Carrying Capacity Step Calculator Estimate one bounded population step under a logistic growth model with a supplied carrying capacity. Breathing Carbon Dioxide Scenario Calculator Estimate carbon dioxide mass from people, hours, and a supplied per-person emission rate. Digital Transaction Energy and Carbon Scenario Calculator Estimate energy and carbon from transaction count, energy per transaction, and an emission factor. Hand Dryer Versus Paper Towel Scenario Calculator Compare supplied energy and paper emissions for repeated hand-drying events. Kaya Identity Emissions Scenario Calculator Calculate an emissions scenario from population, GDP per person, energy intensity, and carbon intensity. Lotka-Volterra Population Step Calculator Calculate one simplified predator-prey population step from supplied interaction parameters. Meat Portion Emission Scenario Calculator Estimate total emissions from portions, portion mass, and a supplied meat emission factor. Passive Building Annual Energy Scenario Calculator Estimate annual energy use and emissions from floor area, energy demand intensity, and an electricity factor. Plug-In Hybrid Emission Scenario Calculator Estimate total energy and emissions for electric and fuel travel shares supplied by the user. Plastic Use Footprint Scenario Calculator Calculate total plastic mass and unrecycled mass from item count, item weight, and recycling fraction. Plastic Reduction Avoided-Item Calculator Calculate avoided items and mass when a baseline use rate is reduced over a selected number of days. Solar Panel Annual Energy Scenario Calculator Estimate annual solar energy from irradiance, panel area, efficiency, and days in the scenario. Tap Water Use Calculator Calculate water volume from flow rate, daily minutes, and number of days. Tree Carbon Benefit Scenario Calculator Estimate cumulative carbon benefit from tree count, annual benefit per tree, and years. Plant-Based Meal Emission Scenario Calculator Estimate emissions difference when a share of meals changes from an animal-based factor to a plant-based factor. Wind Turbine Energy Revenue Scenario Calculator Estimate gross revenue and operating margin from turbine power, capacity factor, price, and operating cost. Reusable Versus Disposable Tree Scenario Calculator Compare supplied emissions for reusable and disposable seasonal trees over multiple seasons. Hydraulic Retention Time Calculator Calculate the average hydraulic residence time of a tank, basin, reactor, or pond from its working volume and flow rate. Fish Mercury Exposure Screening Calculator Estimate average methylmercury dose from fish concentration, portion size, and weekly frequency, then compare the arithmetic with an entered screening reference dose. PAH Benzo[a]pyrene-Equivalent Calculator Combine polycyclic aromatic hydrocarbon concentrations with a documented toxic-equivalency factor list and show the weighted benzo[a]pyrene-equivalent total. Plastic Flow Mass-Balance Calculator Balance an annual plastic input against recycled, incinerated, landfilled, and leaked flows, then show recycling, leakage, and unaccounted shares. Major Event Sustainability Emissions Calculator Build a transparent major-event emissions scenario from construction, travel, accommodation, operations, and other categories, then apply a planning reduction percentage. COVID-Era Before-and-After Pollution Calculator Compare measured pollutant concentrations before and after a COVID-era intervention period and calculate percentage change and concentration-time differences without making a health claim. Tree Value Discounted-Cash-Flow Scenario Calculator Estimate the present value of a tree or timber scenario from harvest revenue, thinning revenue, management costs, upfront cost, timing, and an entered discount rate.

Uniform Acceleration Motion Find final velocity and displacement from initial velocity, constant acceleration, and time. Newton's Second Law Force Calculate force from mass and acceleration, the core relation of classical dynamics. Kinetic Energy Compute the energy of motion from mass and speed. Gravitational Potential Energy Estimate stored energy from mass, height, and Earth's gravity. Work and Power Find mechanical work from force and distance, and power from work over time. Ohm's Law Solver Solve for voltage, current, or resistance in a simple resistive circuit. Density, Mass, and Volume Solver Solve the density relation for whichever of the three quantities is unknown. Molarity Calculator Find solution concentration from moles of solute and litres of solution. Solution Dilution (M1V1 = M2V2) Find the concentration after diluting a stock solution to a new volume. Ideal Gas Law Solver Solve PV = nRT for pressure, volume, moles, or temperature. pH and Hydrogen Ion Calculator Convert between hydrogen-ion concentration and pH in either direction. Free-Fall Time and Impact Speed Drop time and impact velocity for a height with no air resistance. Linear Momentum Momentum from mass and velocity, with kinetic energy for context. Electric Power (P = VI) Power dissipated from voltage and current. Specific Heat Energy (Q = mcT) Thermal energy to change a mass's temperature. Combined Gas Law Solver Find the missing pressure, volume, or temperature between two gas states. 1:1 Titration Concentration Unknown concentration from a 1:1 mole-ratio titration. Solution Preparation Mass Solute mass needed for a target molarity and volume. Projectile Range (Level Ground) Horizontal range of a launch that lands at launch height, vacuum model. Series and Parallel Resistance Equivalent resistance of a resistor list in series or parallel. Wave Speed, Frequency, and Period Relate wave speed, frequency, wavelength, and period. Reaction Percent Yield Efficiency of a chemical reaction from actual vs theoretical product. Moles and Mass Converter Convert between grams and moles with a user-entered molar mass. pH to pOH and Hydroxide Complete the pH/pOH pair plus hydroxide concentration at 25 C. Hardy-Weinberg Genotype Frequencies Genotype frequencies from one allele frequency under equilibrium. Exponential Population Growth Project a population with constant per-capita growth rate. Percent Error Calculator Compare a measured value with a reference value using absolute, percent, and signed percent error. Ideal Gas Pressure Calculator Calculate ideal-gas pressure from amount, temperature, and volume using consistent SI-compatible inputs. Specific Heat Energy Calculator Calculate thermal energy transferred when a material changes temperature. Wavelength and Frequency Calculator Find wavelength, frequency, period, and angular frequency for a periodic wave. Uniform Acceleration Calculator Calculate acceleration, average velocity, and displacement when initial and final velocity are known. Projectile Motion Calculator Estimate flight time, horizontal range, and maximum height for ideal level-ground projectile motion. Boyle’s Law Calculator Find a gas’s unknown pressure or volume when temperature and amount stay constant. Resistance and Electrical Power Calculator Calculate resistance and power from voltage and current using Ohm’s law. Capacitance and Stored Energy Calculator Calculate capacitance and stored energy from charge and voltage. Reynolds Number Calculator Calculate the dimensionless Reynolds number for a flow from density, speed, length, and dynamic viscosity. Reaction Percent Yield Calculator Compare actual product yield with theoretical yield as a percentage. Air Pressure at Altitude Calculator Estimate pressure at altitude with an isothermal ideal-gas atmosphere model. Acceleration from Force and Mass Calculator Calculate acceleration from a net force and an object’s mass using Newton’s second law. Angle of Repose Calculator Estimate the limiting angle of repose from a static friction coefficient. Angular Displacement Calculator Calculate angular displacement and revolutions from constant angular velocity and elapsed time. Angular Frequency Calculator Convert ordinary frequency into angular frequency and period for a repeating cycle. Ideal Air Density Calculator Estimate ideal dry-air density from absolute pressure and temperature. Exponential Attenuation Calculator Calculate remaining intensity and attenuation in decibels for an exponential-loss model. Bulk Modulus Calculator Calculate a material’s bulk modulus from pressure change and fractional volume change. Absolute Humidity Calculator Calculate absolute humidity from water-vapor mass and the volume of air containing it. Acoustic Impedance Calculator Calculate characteristic acoustic impedance from medium density and sound speed. Ballistic Coefficient Calculator Calculate a simplified ballistic coefficient from mass, drag coefficient, and reference area. Bernoulli Equation Calculator Find downstream pressure from two flow states with a steady incompressible Bernoulli model. Two-Body Calorimetry Calculator Estimate the equilibrium temperature when two bodies with known masses and specific heats exchange heat in an isolated model. Blackbody Radiation Power Calculator Estimate thermal radiation power from area, absolute temperature, and emissivity using the Stefan–Boltzmann model. Bragg’s Law Calculator Calculate diffraction angle or lattice spacing with Bragg’s law for a selected wavelength and order. Boltzmann Factor Calculator Calculate the relative Boltzmann factor for an energy difference at an absolute temperature. Bohr Model Energy and Radius Calculator Estimate a hydrogen-like electron energy level and orbital radius from nuclear charge and principal level. RC Capacitor Charge Time Calculator Calculate the time for a resistor-capacitor circuit to reach a selected percentage of its final charge. Frequency Bandwidth Calculator Calculate bandwidth and center frequency from the lower and upper edges of a frequency band. AC Power and Wattage Calculator Estimate real AC power from voltage, current, power factor, and single- or three-phase selection. Average Impact Force Calculator Estimate average stopping force from vehicle mass, speed, and stopping distance in a simplified energy model. Reflection Angle Calculator Calculate the reflected angle and complementary angle to the surface from an entered angle of incidence. Electric-Field Particle Acceleration Calculator Calculate the acceleration magnitude of a charged particle in a uniform electric field from charge and mass. Coordinated-Turn Bank Angle Calculator Estimate the bank angle for a level coordinated turn from speed, turn radius, and gravitational acceleration. Arrow Speed from Kinetic Energy Calculator Calculate an idealized projectile speed from mass and kinetic energy. Avogadro’s Law Volume Calculator Calculate a new gas volume from an initial volume and the ratio of final to initial amount of gas at constant temperature and pressure. Brinell Hardness Number Calculator Calculate a simplified Brinell hardness number from force, indenter diameter, and indentation diameter. Shaft Angle of Twist Calculator Calculate elastic shaft twist from torque, shaft length, shear modulus, and polar second moment of area. Simply Supported Beam Deflection Calculator Estimate center deflection of a simply supported beam under a center point load using an Euler–Bernoulli elastic model. Average Acceleration Calculator Calculate average acceleration and displacement under constant acceleration from initial velocity, final velocity, and elapsed time. Broad-Crested Weir Flow Calculator Estimate ideal flow over a broad-crested weir from crest width, head, discharge coefficient, and gravity. Altitude Temperature Estimate Estimate temperature at altitude using a supplied sea-level temperature and a linear lapse rate. Simply Supported Beam Reaction Calculator Calculate total load, equal support reactions, and maximum bending moment for a simply supported beam under uniform load. Elevator Apparent Weight Calculator Calculate apparent weight for a person or object in a vertical elevator acceleration scenario. Charles’s Law Gas Volume Calculator Calculate a gas volume after a temperature change at constant pressure using absolute temperatures. Cloud Base Height Estimate Estimate cloud-base height from air temperature, dew point, and a supplied temperature-dew-point lapse approximation. Conductivity to Resistivity Calculator Convert electrical conductivity into resistivity using the reciprocal relation. Compton Wavelength Calculator Calculate a particle’s Compton wavelength from its rest mass using Planck’s constant and the speed of light. Bending Stress Calculator Estimate bending stress from bending moment, distance to the outer fiber, and second moment of area. Centrifugal Force Magnitude Calculator Calculate the frame-dependent outward force magnitude associated with circular motion from mass, speed, and radius. Two-Object Momentum Conservation Calculator Calculate total one-dimensional momentum and the shared velocity after a perfectly inelastic collision. Flow Coefficient of Discharge Calculator Estimate a discharge coefficient from measured flow, opening area, and hydraulic head. Uniform Circular Motion Calculator Calculate tangential speed and centripetal acceleration from radius and period. Brake-Specific Fuel Consumption Calculator Convert a fuel mass flow and delivered engine power into brake-specific fuel consumption. Dripping Faucet Water Loss Calculator Estimate water lost from a dripping faucet over a day or a selected number of days. Household Water Demand Calculator Estimate total household water demand from people, daily per-person use, and a selected number of days. Reusable Bag Break-Even Calculator Compare the purchase cost of reusable bags with disposable-bag cost across a planned number of uses. Cigarette Butt Mass Calculator Estimate the collected mass of cigarette butts from a count and an entered average mass per item. Compost Carbon-Nitrogen Mix Calculator Estimate additional brown material needed to reach a selected brown-to-green mass ratio in a compost mix. Focal Length from Sensor Width and Field of View Calculate approximate focal length from a camera sensor dimension and horizontal field of view. Guitar String Tension Calculator Estimate ideal string tension from unit mass, vibrating length, and target frequency. Ground Sample Distance Calculator Estimate ground sample distance per image pixel from altitude, sensor pixel pitch, and focal length. Hyperfocal Distance Calculator Calculate approximate hyperfocal distance from focal length, f-number, and circle of confusion. Thin-Lens Magnification Calculator Calculate image distance and lateral magnification from focal length and object distance using the thin-lens equation. Source and Load Impedance Matching Calculator Calculate reflection coefficient and voltage transfer for a resistive source and load pair. Ideal Cable Impedance Calculator Calculate ideal characteristic impedance from inductance and capacitance per unit length. Photography Exposure Value Calculator Calculate exposure value at ISO 100 and the adjusted exposure value from f-number, shutter time, and ISO. Rainfall Collection Volume Calculator Estimate rainfall volume collected over an area from rainfall depth and a runoff or collection efficiency. Bleach Solution Dilution Calculator Calculate stock solution volume and added water for a target concentration and final volume. Radioactive Half-Life Age Calculator Estimate elapsed age from a half-life, initial activity or fraction, and remaining activity fraction. Diffusion Coefficient from Displacement Calculator Estimate a diffusion coefficient from root-mean-square displacement, elapsed time, and dimensionality. Electrolysis Mass Calculator Estimate deposited or released mass from current, time, molar mass, electron count, and Faraday's constant. Reversible Entropy Change Calculator Calculate entropy change from reversible heat transfer and absolute temperature. Two-Ion Ionic Strength Calculator Calculate ionic strength for a two-species solution from concentrations and charge numbers. Langmuir Adsorption Isotherm Calculator Calculate adsorbed quantity from maximum capacity, affinity constant, and equilibrium concentration. Chemical Oxygen Demand Concentration Calculator Convert oxygen consumed by a sample into chemical oxygen demand concentration. Angular Velocity from Rotations Calculator Calculate angular velocity and rotations per minute from completed rotations and elapsed time. Archimedes Buoyant Force Calculator Calculate buoyant force and equivalent supported mass from fluid density and displaced volume. Hawking Temperature Estimate Estimate ideal Hawking temperature from a nonrotating black-hole mass. Relative Centrifugal Force Speed Calculator Calculate rotor speed in RPM from relative centrifugal force and rotor radius. Mechanical Energy Calculator Calculate gravitational potential energy, kinetic energy, and their sum from mass, height, and speed. Compressibility and Bulk Modulus Calculator Calculate compressibility and bulk modulus from pressure change, initial volume, and volume change. Fluid Drag Force Calculator Calculate ideal drag force from fluid density, drag coefficient, reference area, and speed. Distance to Horizon Calculator Estimate geometric horizon distance from planetary radius and observer height. Debye Length Calculator Estimate the electrostatic screening length of a dilute electrolyte from temperature, relative permittivity, and ionic strength. Activity Coefficient Calculator Estimate a dimensionless activity coefficient from activity and concentration relative to a one-molar standard state. Calibration Curve Inversion Calculator Convert a measured signal into an estimated quantity using a linear calibration slope and intercept. Cubic Unit Cell Density Calculator Calculate ideal crystal density from unit-cell edge length, atoms per cell, and molar mass. Degree of Unsaturation Calculator Calculate the index of hydrogen deficiency from carbon, hydrogen, nitrogen, and halogen counts. Electron Configuration Calculator Generate a ground-state orbital-filling configuration for an element or ion up to atomic number 118. Pauling Electronegativity Difference Calculator Estimate a bond electronegativity difference from heteronuclear and homonuclear bond energies. Concentration Equilibrium Constant Calculator Calculate a concentration-based equilibrium constant from product and reactant concentrations and stoichiometric coefficients. Gibbs Free Energy Change Calculator Calculate Gibbs free-energy change from enthalpy change, entropy change, and absolute temperature. Michaelis-Menten Rate Calculator Calculate ideal initial enzyme reaction rate from maximum rate, Michaelis constant, and substrate concentration. Mass Concentration to Molarity Calculator Convert a mass concentration and molar mass into molar concentration. Alfvén Velocity Calculator Calculate ideal magnetohydrodynamic Alfvén speed from magnetic field and mass density. Angle of Refraction Calculator Calculate a transmitted ray angle using Snell's law and two refractive indices. Brewster Angle Calculator Calculate the incidence angle for zero reflected p-polarized light at an ideal dielectric interface. Compton Scattering Wavelength Calculator Calculate the ideal Compton wavelength shift and scattered wavelength for a photon angle. Critical Damping Calculator Calculate critical damping, damping ratio, and ideal damping regime for a mass-spring system. Coriolis Acceleration Calculator Estimate horizontal Coriolis acceleration magnitude from speed, latitude, and planetary rotation rate. Cricket Chirp Temperature Estimate Estimate outdoor temperature from cricket chirps per minute using a classic empirical relation. Dry Matter and Water Content Calculator Split a material mass into dry matter and water from a stated dry-matter percentage. Feed Conversion Ratio Calculator Calculate feed conversion ratio from feed consumed and live-mass gain. Fertilizer Application Quantity Calculator Estimate total fertilizer mass and bag count from area, application rate, and package size. Growing Degree Units Calculator Estimate cumulative growing degree units from daily high and low temperatures, a base temperature, and days. Grain Bin Capacity and Mass Calculator Estimate filled cylindrical grain-bin volume and grain mass from dimensions, fill fraction, and bulk density. Bushel to Mass Grain Conversion Calculator Convert a bushel count to estimated mass using an entered commodity-specific mass per bushel. Cat Energy Requirement Estimate Estimate resting and factor-adjusted daily energy from a cat's body mass using a transparent power-law model. Dog Age to Human-Year Estimate Estimate an adult-equivalent human age from dog age using a simple first-year, second-year, and later-year model. Dog Water Intake Planning Estimate Estimate a daily water-planning amount from body mass and a visitor-entered millilitres-per-kilogram rate. Gravitational Acceleration from Mass and Radius Calculator Calculate gravitational acceleration from a spherical body’s mass and radius. Biot Number Calculator Calculate the Biot number from a convection coefficient, characteristic length, and material conductivity. Second-Order Damping Ratio Calculator Calculate natural frequency and damping ratio from mass, damping coefficient, and spring stiffness. Decibel Power Gain Calculator Calculate power gain in decibels from output and input power. Drake Equation Scenario Calculator Multiply supplied astronomical and biological factors into a communicating-civilization scenario estimate. Earth Curvature Drop Approximation Calculator Estimate geometric curvature drop over a supplied surface distance using a spherical Earth approximation. Sensible Enthalpy Change Calculator Calculate a simple enthalpy change from mass, specific heat, and temperature change. Faraday Electrolysis Mass Calculator Estimate deposited mass from current, time, molar mass, electron count, and Faraday’s constant. Gear Ratio and Output Speed Calculator Calculate gear ratio, output speed, and ideal torque multiplication from tooth counts and input speed. Hydraulic Radius Calculator Calculate hydraulic radius from flow cross-sectional area and wetted perimeter. Hydrostatic Pressure Calculator Calculate gauge pressure from fluid density, gravitational acceleration, and depth. Inverse-Square Law Calculator Scale a field or intensity from one distance to another under an inverse-square model. Joule Heating Energy Calculator Calculate resistive heating energy from current, resistance, and time. Knudsen Number Calculator Calculate the ratio of molecular mean free path to a characteristic length. Laser Beam Divergence Calculator Estimate full-angle far-field beam divergence from wavelength and initial beam diameter under a diffraction-limited circular-aperture model. Electric Motor Torque from Power and Speed Calculator Calculate ideal shaft torque from mechanical power and rotational speed. Linear Actuator Force from Pressure Calculator Calculate ideal force from pressure and piston area. Lift Coefficient Calculator Calculate a dimensionless lift coefficient from lift force, fluid density, speed, and reference area. Free-Space Path Loss Calculator Calculate ideal free-space radio path loss from frequency and distance. Ideal Transformer Voltage and Current Calculator Calculate secondary voltage and current from turns ratio and primary values under an ideal transformer model. Buoyant Force and Net Force Calculator Calculate ideal buoyant force and the net vertical force from fluid density, displaced volume, gravity, and object mass. Darcy-Weisbach Head-Loss Calculator Calculate frictional head loss and pressure loss in a pipe from length, diameter, speed, friction factor, density, and gravity. Double-Slit Diffraction Fringe Spacing Calculator Calculate ideal double-slit fringe spacing from wavelength, screen distance, and slit separation. Charge-Carrier Drift Velocity Calculator Calculate charge-carrier drift speed from current, carrier density, carrier charge, and cross-sectional area. Heat-Exchanger Effectiveness from NTU Calculator Calculate counterflow heat-exchanger effectiveness from number of transfer units and heat-capacity ratio. Equivalent Isotropically Radiated Power Calculator Calculate ideal effective isotropic radiated power from transmitter power, antenna gain, and cable loss. Elastic Moduli Relationship Calculator Calculate Young’s modulus and bulk modulus from shear modulus and Poisson’s ratio under isotropic elasticity. Electron Speed from Kinetic Energy Calculator Estimate non-relativistic electron speed from kinetic energy. Axial Elongation Calculator Calculate ideal axial elongation from force, member length, cross-sectional area, and Young’s modulus. Energy-Limited Evaporation Rate Calculator Calculate an ideal evaporation mass rate from supplied heat input and latent heat of vaporization. Diopter and Focal-Length Calculator Convert a positive focal length in millimetres to optical power in diopters and back to metres. Density Altitude Approximation Calculator Estimate density altitude from pressure altitude and outside-air temperature using a standard atmosphere approximation. Differential Pressure Calculator Calculate the signed pressure difference between two supplied pressure readings and its absolute magnitude. Delta-to-Wye Resistor Conversion Calculator Convert three delta-connected resistances into equivalent wye-connected resistances. Electric and Magnetic Field Energy Density Calculator Calculate electric, magnetic, and total field energy density from electric field and magnetic flux density. Excess Electrons from Charge Calculator Calculate the magnitude of excess or missing elementary charges represented by a supplied net charge. Factor of Safety Ratio Calculator Calculate a screening factor-of-safety ratio from an allowable or failure strength and a selected working load. Volumetric Flow Rate from Area and Speed Calculator Calculate volumetric flow rate from a flow cross-sectional area and mean speed. Electrical Mobility Calculator Calculate charge-carrier mobility from drift speed and applied electric field. Full-Wave Bridge Rectifier Output Calculator Estimate peak and average rectified output from AC RMS voltage and two diode drops. Average Force from Impulse Calculator Calculate average force from an impulse and the time interval over which it acts. Projectile Flight Time from Height Calculator Calculate the positive flight time for a projectile launched from a known height with no air resistance. Projectile Maximum Height from Launch Point Calculator Calculate a projectile’s highest vertical position and time to apex from launch conditions. Work from Force, Distance, and Angle Calculator Calculate mechanical work from a constant force, displacement, and included angle. Spring-Mass Oscillation Frequency Calculator Calculate angular frequency, frequency, and period for an ideal mass-spring oscillator. Simple Pendulum Period Calculator Calculate the period and frequency of a small-angle simple pendulum. Centripetal Acceleration Calculator Calculate inward acceleration and angular speed for circular motion from speed and radius. Fluid Continuity Flow Calculator Calculate downstream speed and volumetric flow from two cross-sectional areas and one measured speed. Bernoulli Pressure Change Calculator Calculate downstream ideal-fluid pressure from pressure, speed, height, density, and gravity inputs. Specific Heat from Energy Calculator Calculate specific heat capacity from supplied heat energy, mass, and temperature change. Ideal Gas Density Calculator Calculate ideal-gas density from pressure, molar mass, absolute temperature, and the gas constant. Photon Wavelength from Energy Calculator Calculate photon wavelength from photon energy using Planck’s constant and the speed of light. Optical Lens Power Calculator Calculate optical power in diopters from a thin-lens focal length. Work from Kinetic Energy Change Calculator Calculate net work from mass and initial and final speeds using the work-energy theorem. Thermal Efficiency from Work and Heat Calculator Calculate thermal efficiency and rejected heat from useful work and input heat. Thermal Conduction Resistance Calculator Calculate planar thermal resistance and steady heat-transfer rate through a material slab. Thermal Radiation Power Calculator Calculate idealized radiative power from emissivity, area, and absolute temperature. Electric Field from a Point Charge Calculator Calculate electric-field magnitude and potential from a point charge and distance. Snell’s Law Refraction Angle Calculator Calculate a refracted angle from two refractive indices and an incident angle. Critical Angle Calculator Calculate the critical angle for total internal reflection from a higher-index medium to a lower-index medium. Cube Density from Mass and Side Calculator Calculate the density of a cube from its mass and side length, with the cube volume shown for checking. Darcy’s Law Flow Rate Calculator Estimate porous-medium flow rate from permeability, area, pressure difference, viscosity, and flow length. Darcy Friction Factor from Head Loss Calculator Rearrange the Darcy–Weisbach relation to estimate a dimensionless friction factor from measured head loss and pipe conditions. Froude Number Calculator Calculate the Froude number for a flow or moving body from speed, characteristic length, and gravity. Heat Capacity from Energy and Temperature Change Calculator Calculate the heat capacity of a body from energy transferred and the resulting temperature change. Heat Transfer Coefficient Calculator Estimate a convective heat-transfer coefficient from heat rate, area, and temperature difference. Hydraulic Gradient Calculator Calculate hydraulic gradient from head loss and the flow distance between two points. Lorentz Force Component Calculator Calculate electric and magnetic force components on a moving charge under a stated same-direction component convention. Force Between Parallel Current-Carrying Wires Calculator Calculate the ideal magnetic force between two long parallel current-carrying wires. Mach Number Calculator Calculate Mach number from an object's speed and the local speed of sound. Mechanical Advantage Calculator Calculate ideal mechanical advantage from load force and applied effort force. Newton’s Law of Cooling Calculator Estimate an object's temperature after a time interval using a first-order Newton cooling model. Nusselt Number Calculator Calculate the dimensionless Nusselt number from a heat-transfer coefficient, characteristic length, and thermal conductivity. Physical Pendulum Period Calculator Calculate the small-angle period and frequency of a rigid-body physical pendulum from inertia, mass, pivot distance, and gravity. Pipe Velocity from Flow Rate and Diameter Calculator Calculate mean pipe velocity from volumetric flow rate and circular pipe diameter. Prandtl Number Calculator Calculate the Prandtl number from specific heat, dynamic viscosity, and thermal conductivity. Lensmaker’s Equation Calculator Calculate thin-lens focal length and optical power from refractive indices and the two surface radii. Enzyme Activity from Product Formation Calculator Calculate enzyme activity from the amount of product formed, reaction time, and sample volume. Electrochemical Cell EMF Calculator Calculate the ideal cell electromotive force from cathode and anode reduction potentials. Graham's Law of Effusion Calculator Compare gas effusion or diffusion rates from the molar masses of two gases. Heat of Combustion per Mass Calculator Calculate the energy released per unit mass from a combustion measurement. Isoelectric Point from Adjacent pKa Values Calculator Estimate the isoelectric point from the two pKa values that bracket the neutral zwitterion. Kp from Kc Equilibrium Constant Calculator Convert a concentration-based equilibrium constant to a pressure-based constant for a gas reaction. Born-Landé Lattice Energy Calculator Estimate ionic lattice energy per mole from charges, interionic distance, Madelung constant, and Born exponent. Atmospheric Water-Vapor Mixing Ratio Calculator Calculate the water-vapor mixing ratio from vapor pressure and total atmospheric pressure. Miller Indices from Lattice Intercepts Calculator Convert integer lattice intercepts into the smallest whole-number Miller indices for a crystal plane. Nernst Equation Cell Potential Calculator Calculate nonstandard electrochemical potential from standard potential, temperature, electron count, and reaction quotient. Normality from Molarity Calculator Calculate solution normality and total equivalents from molarity, reaction-equivalent factor, and volume. Osmotic Pressure Calculator Calculate ideal osmotic pressure from solute molarity, van't Hoff factor, and temperature. Percent Ionic Character Calculator Estimate percent ionic character from the electronegativity difference using the Pauling relationship. Gibbs Phase Rule Degrees of Freedom Calculator Calculate degrees of freedom from the number of components, phases, and externally fixed intensive variables. pKa from Ka Calculator Convert an acid dissociation constant into pKa using the base-10 logarithm. Temperature Coefficient Q10 Calculator Calculate the Q10 temperature coefficient from two rates measured at two temperatures. Reaction Quotient from Activities Calculator Calculate a simple reaction quotient from product and reactant activities with explicit stoichiometric exponents. Saponification Value Calculator Calculate milligrams of potassium hydroxide required per gram of oil or fat from a blank and sample titration. Water Hardness as CaCO3 Calculator Convert dissolved calcium and magnesium concentrations into equivalent water hardness as calcium carbonate. Young-Laplace Pressure Calculator Calculate ideal gauge pressure across a spherical liquid interface from surface tension and radius. Moment of Inertia Shape Calculator Calculate mass moment of inertia for common uniform rods, disks, hoops, and rectangular plates about a stated central or end axis. Three-Phase Motor Current Calculator Estimate the line current required by a balanced three-phase motor from output power, voltage, power factor, and efficiency. Sheet-Metal Bend Allowance Calculator Estimate bend allowance and flat-pattern length from bend angle, inside radius, thickness, K-factor, and straight legs. Brake Mean Effective Pressure Calculator Calculate brake mean effective pressure from engine torque, displacement, and two- or four-stroke cycle selection. Engine Airflow CFM Calculator Estimate theoretical engine airflow from displacement, engine speed, volumetric efficiency, and engine cycle. Vertex Distance Power Conversion Calculator Convert an optical power between two vertex planes using the thin-lens vertex-distance relation. Schwarzschild Radius Calculator Calculate the ideal event-horizon radius of a nonrotating, uncharged black hole from its mass. Molar Curie Constant Calculator Estimate the SI molar Curie constant from an effective magnetic moment expressed in Bohr magnetons. Curie-Law Magnetic Susceptibility Calculator Calculate ideal molar magnetic susceptibility from a Curie constant and absolute temperature. Daylight Hours by Latitude Calculator Estimate daylight duration from latitude, day of year, and axial tilt using a simple solar-declination model. Gear Diametral Pitch Calculator Calculate diametral pitch, circular pitch, and metric module from gear teeth and pitch diameter. Flywheel Energy Storage Calculator Estimate usable rotational energy between maximum and minimum flywheel speeds from moment of inertia. Geometric Propeller Pitch Calculator Estimate theoretical propeller pitch from blade angle and the reference radius of the blade section. Four-Wheel-Drive Crawl Ratio Calculator Calculate total low-range crawl ratio from first gear, transfer-case reduction, and final-drive ratio. Barn and Pole Relativity Calculator Explore Lorentz contraction and the relativity-of-simultaneity gap in a pole-and-barn thought experiment. Ideal Electric Dipole Field Calculator Estimate the far-field magnitude and potential of an ideal electric dipole on its axial or equatorial line. Exoplanet Transit Depth Calculator Estimate the fractional and percentage drop in starlight when a planet crosses its star in a central transit. Fresnel Zone Radius Calculator Calculate a radio-link Fresnel-zone radius and diameter at a point between two antennas. Fermi–Dirac Occupation Calculator Estimate the equilibrium occupation probability of an energy state from its energy, Fermi level, and temperature. Hall Coefficient Calculator Calculate Hall coefficient and a one-carrier density estimate from Hall voltage, sample thickness, current, and magnetic field. Harmonic Wave Equation Calculator Evaluate displacement, wave speed, angular frequency, and wave number for a sinusoidal traveling wave. Helical Coil Geometry Calculator Estimate axial length and wire path length for a regular helical coil from diameter, turn count, and pitch. Helmholtz Resonator Frequency Calculator Estimate the resonance frequency of a bottle-like Helmholtz resonator from opening area, cavity volume, neck geometry, and sound speed. RC High-Pass Filter Calculator Calculate cutoff frequency, magnitude gain, gain in decibels, and phase for an ideal first-order RC high-pass filter. Hohmann Transfer Calculator Estimate the two ideal impulse burns and transfer time between two coplanar circular orbits around the same central body. Hubble's Law Calculator Estimate a distant galaxy's recession velocity from distance and an entered Hubble constant. Hydraulic Conductivity Calculator Estimate Darcy discharge from hydraulic conductivity, cross-sectional area, head difference, and flow length. Hydraulic Jump Calculator Estimate sequent depth, depth ratio, and idealized energy loss for a rectangular-channel hydraulic jump. Log Mean Temperature Difference Calculator Calculate the logarithmic mean temperature difference between two streams in a counterflow or parallel-flow heat-exchanger setup. Orifice Flow Rate Calculator Estimate volumetric flow through a sharp-edged orifice from discharge coefficient, area, pressure difference, and fluid density. Poiseuille Flow Calculator Calculate ideal laminar flow through a circular tube from pressure drop, radius, length, and dynamic viscosity. Stokes' Law Drag Calculator Estimate the low-speed viscous drag on a small spherical particle moving through a fluid. Mean Free Path Calculator Estimate the mean distance and mean time between molecular collisions in a dilute ideal gas. Optical Density Calculator Calculate optical density, transmission, and attenuation from incident and transmitted light intensity. Radiation Pressure Calculator Calculate ideal light pressure and force for a perfectly absorbing or perfectly reflecting surface. Net Positive Suction Head Calculator Calculate available net positive suction head from pump suction pressure, fluid vapor pressure, density, and gravity. Pneumatic Cylinder Force Calculator Estimate ideal and efficiency-adjusted push force from air pressure and piston bore diameter. Rocket Specific Impulse Calculator Calculate specific impulse and equivalent exhaust velocity from rocket thrust and propellant mass-flow rate. Atom and Ion Composition Calculator Calculate mass number, neutron count, and electron count from proton count, neutron count, and ionic charge. Boiling Point from Vapor Pressure Calculator Estimate a liquid's boiling temperature at a target pressure with a two-point Clausius–Clapeyron model. Boiling Point at Altitude Calculator Estimate standard-atmosphere pressure and water-like boiling temperature at altitude using a barometric and Clausius–Clapeyron approximation. Chemical Equation Balancer Balance a chemical equation by conserving the elements in the entered reactant and product formulas. Combustion Analysis Empirical Formula Calculator Estimate an empirical formula from measured masses of carbon, hydrogen, oxygen, and nitrogen in a sample. Hydrocarbon Combustion Stoichiometry Calculator Calculate ideal oxygen, carbon-dioxide, and water amounts for complete combustion of a hydrocarbon CxHy. Crude Protein from Nitrogen Calculator Estimate crude protein mass and percentage from measured nitrogen and an entered nitrogen-to-protein factor. Tank Detention Time Calculator Calculate theoretical detention time from effective tank volume and flow rate, with hours and days shown separately. Effective Nuclear Charge Calculator Estimate effective nuclear charge with a transparent, simplified Slater-rule screening scenario. Molar Ratio from Masses Calculator Convert two chemical masses to moles and compare their amount ratio using entered molar masses. Acid–Base Neutralization Volume Calculator Estimate the volume of one acid or base solution required to neutralize another from concentration, volume, and equivalent stoichiometry. Integrated Rate Constant Calculator Calculate a zero-, first-, or second-order rate constant from initial concentration, final concentration, and elapsed time. Serial Dilution Calculator Calculate the final concentration and cumulative dilution from a repeated per-step retained fraction. Total Dissolved Solids Estimate Estimate total dissolved solids from specific conductance with an entered conversion factor and optional local intercept. Vapor Pressure from Temperature Calculator Estimate vapor pressure at a target temperature from a reference pressure and enthalpy of vaporization using Clausius–Clapeyron. First-Order Crossover Frequency Calculator Estimate the transition frequency and time constant of an ideal first-order RC crossover network. Valve Flow Coefficient (Cv) Calculator Estimate liquid flow from a valve flow coefficient, pressure drop, and specific gravity. Sound Level Distance Attenuation Calculator Estimate free-field sound-level change when the distance from a point source changes. Piston Engine Displacement Calculator Calculate swept engine displacement from cylinder bore, stroke, and cylinder count. Friction Coefficient from Force Calculator Estimate a static or kinetic friction coefficient from friction force and normal force. Gay-Lussac Pressure–Temperature Law Calculator Estimate a gas pressure after a temperature change at constant volume and fixed amount of gas. Magnetic Permeability Calculator Calculate absolute and relative magnetic permeability from magnetic flux density and magnetic field strength. Mass–Spring Natural Frequency Calculator Calculate angular frequency, frequency, and period for an ideal undamped mass–spring oscillator. AC Power Factor Calculator Calculate apparent power, power factor, reactive power, and phase angle from real power and RMS voltage/current. Four-Band Resistor Color Code Calculator Decode the nominal resistance and tolerance range of a standard four-band resistor. Resistor Johnson Noise Calculator Estimate ideal Johnson–Nyquist voltage and current noise for a resistor over a selected bandwidth. Sabine Reverberation Time Calculator Estimate room reverberation time from room volume and total equivalent absorption area. Relative Humidity from Dew Point Calculator Estimate relative humidity and vapor-pressure deficit from air temperature and dew-point temperature. Piston Force from Pressure Calculator Calculate ideal force on a circular piston from net pressure and piston diameter. Mean Piston Speed Calculator Calculate mean piston speed from engine stroke and rotational speed. API Gravity and Specific Gravity Calculator Convert petroleum specific gravity at 60 °F into API gravity, or reverse the relation for a transparent planning check. Exhaust Pipe Diameter from Flow Rate Calculator Estimate the circular flow area and internal diameter needed for a chosen volumetric flow and target average gas velocity. Lifetime-Limited Laser Linewidth Calculator Estimate the Fourier-limited linewidth associated with a finite excited-state lifetime and show the corresponding coherence-time scale. Diffraction-Limited Laser Spot Size Calculator Estimate the Airy-disk diameter, radius, and area for a circular aperture or focused beam using wavelength and focal geometry. Magnetic Dipole Moment Calculator Calculate the ideal magnetic dipole moment of a multi-turn current loop from turns, current, and loop area. Magnus-Style Lift Force Calculator Estimate a transverse aerodynamic force using density, speed, reference area, and a supplied lift coefficient for a spinning or curved-flow object. Spherical Mirror Equation Calculator Find image distance, magnification, and mirror curvature from focal length and object distance using the signed mirror convention. Particle Number Density Calculator Calculate the number of particles per volume and the volume represented by a supplied particle count. Porosity and Kozeny–Carman Permeability Estimate Calculate void fraction and an idealized intrinsic permeability estimate from porosity, grain diameter, and a supplied Kozeny constant. Power-to-Weight Ratio Calculator Compare a machine or vehicle's power with its mass in W/kg, kW per metric tonne, and horsepower per metric tonne. Principal Stress and Maximum Shear Calculator Resolve a two-dimensional stress state into principal stresses, maximum in-plane shear stress, and principal-angle orientation. Pulley Mechanical Advantage Calculator Estimate ideal and efficiency-adjusted effort, mechanical advantage, and rope travel for a block-and-tackle style pulley arrangement. Two-Body Recoil Energy Calculator Estimate recoil velocity and kinetic energy from an ideal isolated two-body momentum exchange. Two-Force Resultant Calculator Add two planar force vectors by magnitude and angle, returning Cartesian components, resultant magnitude, and direction. Root-Mean-Square Molecular Speed Calculator Calculate the ideal-gas root-mean-square molecular speed from temperature and molar mass. Signal-to-Noise Ratio Calculator Convert signal and noise power into a linear ratio, decibel value, and percentage noise relative to the signal. Simple Harmonic Motion Position Calculator Evaluate displacement, velocity, and acceleration at a time in ideal sinusoidal motion from amplitude, frequency, and phase. Electromagnetic Skin Depth Calculator Estimate the depth at which a sinusoidal electromagnetic field falls to 1/e in a conductor from frequency, permeability, and conductivity. Sound Absorption Coefficient Calculator Calculate the absorbed energy and normal-incidence absorption coefficient from incident and reflected sound energy. Quadratic-Drag Terminal Velocity Calculator Estimate terminal speed when gravitational force balances quadratic drag in a fluid. Latitude and Longitude Distance Calculator Estimate great-circle distance and initial bearing between two geographic coordinates using a transparent spherical Earth model. Mass Percent of a Solution Calculator Calculate the mass percentage of a solute in a solution and show the corresponding mass fraction and parts-per-million estimate. Molar Mass from Gas Measurements Calculator Estimate a gas sample's molar mass from measured mass, pressure, volume, and absolute temperature using the ideal-gas relation. Protein Solubility Assay Calculator Convert dissolved protein mass and sample volume into soluble concentration, recovery percentage, and undissolved remainder for a transparent assay summary. Radioactive Activity after Half-Lives Calculator Estimate remaining activity, undecayed fraction, decay constant, and activity lost after a chosen elapsed time and half-life. Pellet Resuspension Concentration Planner Estimate final cell concentration and the buffer volume needed to resuspend a pellet to a selected target concentration. Stoichiometric Theoretical Yield Calculator Calculate product moles and mass from a limiting-reactant amount, balanced-equation coefficients, and product molar mass. General Stoichiometric Titration Calculator Calculate an analyte concentration from titrant concentration, measured volumes, and balanced-reaction coefficients beyond the simple 1:1 case. Two-Photon Absorption Rate Calculator Estimate weak-field two-photon absorption events from a cross section, photon flux, and number of absorbing molecules. Water Saturation Vapor Pressure Calculator Estimate saturation vapor pressure over liquid water or ice from temperature using a pressure-adjusted Buck formulation and show the result in common pressure units. Thin-Film Interference Calculator Estimate the optical path difference and nearest constructive or destructive reflection condition for a uniform thin film. Afocal Laser Beam Expander Calculator Calculate ideal beam diameter, angular-divergence ratio, and afocal magnification from two lens focal lengths. Manometer Pressure Difference Calculator Calculate gauge and absolute pressure from a manometer liquid density, column-height difference, gravity, and atmospheric pressure. Two-Body Reduced Mass Calculator Calculate the reduced mass and relative-motion kinetic energy of a two-body system from two masses and their relative speed. Elastic Section Modulus Calculator Calculate second moment of area, elastic section modulus, and simple elastic bending stress for common symmetric cross-sections. Synodic Period Calculator Calculate the time for two orbiting bodies to return to the same relative angular configuration from their orbital periods. Thermal Diffusivity Calculator Calculate thermal diffusivity from thermal conductivity, density, and specific heat capacity. Aircraft Wing Loading Calculator Calculate aircraft wing loading from mass, gravity, and projected wing planform area, with optional customary-unit output. Shear Strain and Stress Calculator Calculate engineering shear strain, angular distortion, and elastic shear stress from lateral displacement, layer height, and shear modulus. Von Mises Stress Calculator Calculate equivalent von Mises stress, yield utilization, and remaining stress margin from three principal stresses. Gauss's Law Flux Calculator Calculate electric flux, enclosed charge, and the ideal spherical-surface electric field using Gauss's law. J-Pole Antenna Dimension Calculator Estimate the wavelength, half-wave radiating section, quarter-wave matching section, and total 3/4-wave J-pole length from frequency. Lumen and Illuminance Calculator Calculate luminous flux from candela and solid angle, then estimate illuminance in lux and foot-candles over an area. Lux to Foot-Candle Converter Convert an illuminance value between lux and foot-candles using the NIST conversion factor. Minute of Angle Target-Size Calculator Convert a minute-of-angle value and viewing distance into the corresponding linear size and angular size in radians. AM Modulation Index Calculator Calculate amplitude-modulation depth, envelope limits, sideband amplitudes, and ideal single-tone AM power ratios. NE555 Astable Frequency Calculator Estimate the oscillation frequency, period, timing intervals, and duty cycle of a standard NE555 astable circuit. Redshift and Blueshift Calculator Calculate spectral redshift or blueshift from rest and observed wavelengths, with a low-redshift velocity approximation and scale factor. Rydberg Equation Calculator Calculate a hydrogen-like spectral transition wavelength, wavenumber, and photon energy from atomic number and energy levels. Solenoid Magnetic Field Calculator Estimate the internal magnetic field, magnetic field strength, and turns-per-length of an ideal long solenoid. Cell and Solution Dilution Calculator Use C₁V₁ = C₂V₂ to find the stock volume, diluent volume, and dilution factor for a target concentration and final volume. CO₂ Grow Room Gas Requirement Calculator Estimate the theoretical CO₂ gas volume, amount, and mass needed to raise a sealed room from one measured ppm level to another at entered temperature and pressure. Grass Seed Quantity Calculator Estimate the base and purchase quantity of grass seed from a rectangular area, a label seeding rate, and an optional allowance for uneven establishment. Mulch Volume and Bag Calculator Calculate mulch volume from a rectangular area and layer depth, then estimate the liters and bags needed after an explicit waste allowance. Plant Population and Row Spacing Calculator Estimate how many planting rows, plants per row, and total planting positions fit inside a rectangular bed using center-to-center spacing. Potting Soil Volume and Bag Calculator Estimate the fill volume for repeated rectangular containers, apply a fill percentage, and round the result to whole bags. Raised Bed Soil Volume Calculator Calculate the soil volume for a rectangular raised bed and estimate bag count after a chosen settling or top-up allowance. Tree Spacing and Hectare Density Calculator Estimate theoretical tree density from row and in-row spacing and scale it to a selected land area without treating the result as a stocking prescription. Vegetable Row Seed Quantity Calculator Estimate seed positions, adjusted seed count, and seed mass for a row using spacing, germination, establishment, and seeds-per-gram inputs. Water-Soluble Fertilizer Mass from ppm Calculator Convert a chosen nutrient target in ppm and solution volume into nutrient mass, product mass from a label percentage, and whole packets. Isotope-Weighted Atomic Mass Calculate an element's average atomic mass from isotope masses and their percentage abundances. Particles, Moles, and Mass Bridge Convert a particle count or mole amount into the corresponding moles, particles, and mass for a supplied molar mass. Mass and Molar Concentration Calculate mass concentration and molar concentration from solute mass, final solution volume, and molar mass. Double Bond Equivalent Calculator Estimate degrees of unsaturation from carbon, hydrogen, nitrogen, and halogen counts in an organic formula. Solution Dilution Factor Calculate how many times a stock solution must be diluted to reach a target concentration and show the final-to-stock fraction. Henderson-Hasselbalch Buffer Calculator Estimate buffer pH from pKa and the conjugate-base-to-acid concentration ratio. Hydrogen-Ion Concentration and pH Convert between pH and hydrogen-ion concentration while showing pOH under the 25 °C dilute-aqueous convention. Precipitation Net-Ionic Equation Builder Build a bounded precipitation net-ionic equation from selected aqueous ions and a supported insoluble product pair. Percent w/v to Molarity Converter Convert grams-per-100-milliliters percentage concentration into molarity using the solute molar mass. Common Chemical Formula Name Lookup Look up the common name and formula class for a bounded set of frequently encountered chemical formulas. Parallel-Plate Capacitance and Stored Energy Estimate the capacitance, charge, stored energy, and electric field of an ideal parallel-plate capacitor. Quadratic Drag Force and Terminal Speed Calculate idealized quadratic drag force and the corresponding terminal speed for an object moving through a fluid. Poisson's Ratio from Axial and Lateral Strain Calculate Poisson's ratio and the dimensional changes of a specimen from signed axial and lateral strains. Mass Moment of Inertia for Common Shapes Calculate the mass moment of inertia about a stated idealized axis for a point mass, rod, hoop, disk, sphere, or cylinder. Normal Force on a Supported Incline Estimate the contact normal force for a mass on an incline with an optional force directed away from or toward the surface. Circular Orbital Period Calculate the period, circular speed, and local gravitational acceleration for an ideal circular orbit around a central mass. Laminar Pipe Flow by Hagen–Poiseuille Estimate flow rate, mean speed, and Reynolds number for a pressure-driven Newtonian fluid in a circular pipe. One-Dimensional Impulse and Momentum Calculate initial and final momentum, impulse, average force, and kinetic-energy change from a one-dimensional velocity change. Drake Equation Civilization Estimate Estimate the number of detectable technological civilizations from the seven factors in the Drake equation. Binoculars Angular-Size Range Estimate the distance to a target of known height from its apparent angular size and binocular magnification. Vehicle Center of Mass from Axle Loads Estimate a vehicle's longitudinal center of mass from front and rear axle loads and wheelbase. Elevated Vehicle Jump Distance Estimate flight time, horizontal distance, and impact speed for an ideal projectile launched from an elevated ramp. Ideal Constant-Acceleration Interstellar Travel Estimate one-way travel time for a symmetric accelerate–cruise–decelerate journey to a stated distance. Light Frequency from Wavelength Calculate electromagnetic-wave frequency, period, photon energy, and wavenumber from wavelength in vacuum. Fulcrum Lever Balance Find the effort force, mechanical advantage, and ideal pivot reaction for a two-force lever in static balance. Schwarzschild Gravitational Time Dilation Estimate the proper time elapsed near a spherical nonrotating mass compared with a distant coordinate-time interval. Hair-Width Diffraction Estimate Estimate the first diffraction minimum angle and screen displacement for light diffracted by an opaque hair-sized obstacle. Hydrogen-Like Atom Energy Transition Calculate Bohr-model energy levels, orbit radii, and photon wavelength for a one-electron ion transition. Lightning Distance from Thunder Delay Estimate how far away a lightning flash was from the time between seeing the flash and hearing thunder. Radar Horizon Range Estimate the geometric line-of-sight range to a target from radar antenna height, target height, and an effective Earth radius. Luminosity from Flux and Distance Calculate a source's total radiated power from measured energy flux and distance using the inverse-square relationship. Quantum Number Validity and Orbital Capacity Check a set of electron quantum numbers and calculate its shell, subshell, orbital, and electron capacities. Poise and Stokes Viscosity Converter Convert dynamic viscosity to SI and poise units and derive kinematic viscosity in stokes from density. 3D Acceleration Magnitude Find the total acceleration magnitude and g-equivalent from perpendicular x, y, and z acceleration components. Aircraft Ground Speed with Wind Vector Calculate an aircraft's ground speed and track from airspeed, heading, and meteorological wind direction and speed. Foot-Pounds of Work and Energy Calculate mechanical work in foot-pounds-force from a force, distance, and included angle, then convert it to joules. Laser Beam Irradiance Estimate optical power density from laser power and circular spot diameter, with watts per square metre and decibel output. Coefficient of Performance Calculate a heating or cooling system's coefficient of performance from useful output energy and supplied input energy. Cube-Root Blast-Scaling Radius Scale a reference blast-effect radius to a different TNT-equivalent yield with the cube-root scaling relationship. Capacitive Transformerless Supply Sizing Estimate capacitive reactance, reactive VA, and series-capacitor value for a target RMS current at a stated AC voltage and frequency. Mass from Density and Volume Calculate an object's mass from its density and volume while returning the SI volume and specific-volume equivalents. Free Fall with Quadratic Air Resistance Estimate fall time, final speed, and terminal speed for an object dropped from rest under a constant quadratic-drag model. Root-Mean-Square Molecular Speed Calculate the root-mean-square speed of ideal-gas molecules from temperature and molar mass. Sound Wavelength from Speed and Frequency Calculate a sound wave's wavelength and period from its propagation speed and frequency. Surface Tension from Force and Length Calculate surface tension from a measured force acting along a liquid-surface length. van der Waals Gas Pressure Calculate non-ideal gas pressure from amount, temperature, volume, and van der Waals constants. Vickers Hardness Number Calculate Vickers hardness from indentation load and the two measured diagonals of a square-pyramidal diamond impression. Energy to TNT Equivalent Convert an energy value in joules to an equivalent mass of TNT using the standard energy-equivalence factor. Specific Gas Constant Calculate a gas's specific gas constant from its molar mass using the universal molar gas constant. Wavenumber from Wavelength Calculate spatial wavenumber, cycles per metre, and frequency from wavelength and propagation speed. Wind Correction Angle Solve the horizontal wind triangle for a heading correction, groundspeed, and crosswind components along a chosen course. Wheatstone Bridge Balance Calculate the unknown resistance at balance and the detector voltage for a four-resistor Wheatstone bridge. Apparent Power in kVA Calculate single-phase or balanced three-phase apparent power, real power, and reactive power from RMS voltage, current, and power factor. Voltage Regulation Calculate voltage regulation from no-load and full-load output voltage and show the resulting load drop. Young's Modulus from Stress and Strain Calculate tensile or compressive Young's modulus from force, cross-sectional area, original length, and extension. RMS Voltage for a Sine Wave Convert sinusoidal peak voltage to RMS, peak-to-peak, average-rectified voltage, and resistive-load power. Water Pressure at Depth Calculate gauge and absolute hydrostatic pressure below a fluid surface from depth, density, surface pressure, and gravity. Telescope Field of View Estimate telescope magnification, true angular field of view, and exit pupil from telescope and eyepiece specifications. Horsepower to Amps Estimate motor input current from mechanical horsepower, voltage, phase, power factor, and efficiency. Open-Channel Flow (Manning Equation) Estimate uniform flow velocity and discharge in a rectangular open channel from geometry, slope, and Manning roughness. Speed of Sound in a Solid Estimate longitudinal sound speed in a solid from Young's modulus and density, then calculate travel time over a path. Solar Elevation and Azimuth Angle Calculate the Sun's elevation, zenith, and compass azimuth from latitude, solar declination, and hour angle. Sunrise and Sunset from Solar Geometry Estimate sunrise, sunset, daylight duration, and solar noon from latitude, declination, longitude, time zone, and equation of time. True Airspeed from Equivalent Airspeed Estimate true airspeed from equivalent airspeed and actual air density using the density-ratio relationship. Water Dynamic Viscosity by Temperature Estimate liquid-water dynamic viscosity from temperature using a compact atmospheric-pressure correlation. Watt-Hours from Power and Time Calculate energy use in watt-hours, kilowatt-hours, and joules from power, runtime, quantity, and efficiency. Wave Velocity from Wavelength and Frequency Calculate wave speed, period, and angular frequency from wavelength and ordinary frequency. Wet-Bulb Temperature Estimate wet-bulb temperature from air temperature and relative humidity with the published Stull approximation. Vertical Exaggeration Calculate the vertical exaggeration of a profile from its horizontal and vertical map scales. Microbial Log Reduction Convert initial and surviving organism counts into log reduction, remaining fraction, and percent reduction. qPCR Amplification Efficiency Convert the slope of a qPCR standard curve into amplification efficiency and fold amplification per cycle. Mutation Frequency from Counts Calculate the observed fraction of mutant cells or organisms and express it as a percent or per-million frequency. Plant Water Potential Estimate solute potential from molarity, van't Hoff factor, and temperature, then combine solute, pressure, and gravitational terms. Tree Height from Clinometer Angles Estimate tree height from horizontal distance, top and base sight angles, and observer eye height. Wire Resistance from Resistivity Calculator Calculate the resistance of a uniform conductor from material resistivity, length, and cross-sectional area. VSWR and Return Loss Calculator Convert a reflection-coefficient magnitude into voltage standing-wave ratio, return loss, and reflected power. Stopping Distance Calculator Estimate reaction distance, braking distance, and total stopping distance from speed, reaction time, and deceleration. Inclined-Plane Force Calculator Estimate normal force, downhill gravity, kinetic friction, and the force needed to move an object up an incline at constant speed. LED Series Resistor Calculator Choose a current-limiting resistor for one or more LEDs in series and estimate the resistor voltage and power. Darcy–Weisbach Pipe Friction Loss Calculator Estimate pipe friction head loss and pressure loss from the Darcy friction factor, length, diameter, velocity, and fluid density. Air Kinematic Viscosity Calculator Calculate air kinematic viscosity from dynamic viscosity and density, with a convenient centistokes conversion. Polar Moment of Area Calculator Find the polar second moment of area for a solid circular shaft or an annular tube and show its torsional section modulus. Pump Horsepower Calculator Estimate hydraulic and brake horsepower from pump flow, head, specific gravity, and pump efficiency. Resultant Velocity Calculator Combine perpendicular velocity components to find resultant speed, horizontal direction, and elevation angle. Ripple Capacitor Size Calculator Estimate the minimum bulk capacitance needed for a switching-converter ripple limit while exposing the ESR contribution. Ideal Flyback Converter Calculator Estimate flyback output voltage and the duty cycle needed for a target from input voltage, turns ratio, and diode drop. Ideal Forward Converter Calculator Estimate forward-converter output voltage and target duty cycle from input voltage, transformer turns ratio, and diode drop. Decibel Ratio Calculator Convert a positive measured-to-reference power or amplitude ratio into decibels and percentage change. Kinematic Displacement Calculator Calculate one-dimensional displacement, final position, final velocity, and average velocity under constant acceleration. Cylinder Density Calculator Calculate the volume and density of a uniform solid cylinder from its mass, diameter, and height. Magnetic Declination Bearing Correction Calculator Convert a magnetic bearing to a true bearing using a supplied local magnetic declination value. Circular Orbit Period and Speed Calculator Estimate circular-orbit period, speed, and local escape speed from central mass and orbital radius. Electric Dipole Moment Calculator Calculate the magnitude of an electric dipole moment from separated charge and charge-center distance. Relativistic Length Contraction Calculator Calculate the length observed parallel to motion when an object travels at a chosen fraction of light speed. Rocket Engine Thrust Calculator Estimate rocket thrust from exhaust mass flow, exhaust velocity, nozzle area, and exit-to-ambient pressure difference. Marine Propeller Slip Calculator Estimate apparent propeller slip from engine speed, gear ratio, propeller pitch, and measured boat speed. Fully Restrained Thermal Stress Calculator Estimate axial thermal stress, thermal strain, and free expansion for a linearly elastic member that cannot expand. Virtual Temperature Calculator Estimate meteorological virtual temperature from air temperature and water-vapor mixing ratio. CFD y⁺ Wall-Distance Calculator Calculate dimensionless wall distance y⁺ from first-cell distance, friction velocity, and kinematic viscosity. Density from Mass and Volume Calculator Calculate density and specific volume from a mass and volume measured on the same unit basis. Electrical Power Calculator Estimate real power, apparent power, energy, and resistance from voltage, current, power factor, and operating time. Frequency to Wavelength Calculator Convert frequency and wave speed into wavelength, period, and wavenumber for a stated medium or signal. Rolling Resistance Force and Power Calculator Estimate level-road rolling-resistance force, power, and work from mass, coefficient, speed, and distance. Column Slenderness Ratio Calculator Calculate effective length and KL/r slenderness ratio from unsupported length, effective-length factor, and radius of gyration. Reaction Time Distance Calculator Estimate distance traveled during a stated reaction time at a stated speed. Speed of Sound in Dry Air Calculator Estimate the speed of sound in dry air from temperature using a stated near-room-temperature approximation. Moisture Content Wet and Dry Basis Calculator Calculate water mass and moisture content on wet and dry bases from wet and dry sample masses. Gold Volume to Weight Estimate Calculator Estimate pure-gold mass equivalent and troy ounces from volume and an entered purity percentage. Generator Useful Power Calculator Estimate useful real output and energy from a generator apparent-power rating, power factor, efficiency, and operating time. Supersonic Isentropic Flow Calculator Calculate ideal supersonic flow ratios, critical-area ratio, Mach angle, and Prandtl-Meyer angle from Mach number and heat-capacity ratio. Weak Oblique Shock Calculator Estimate weak attached-shock angle and downstream flow ratios from upstream Mach number, turning angle, and specific-heat ratio. Prandtl-Meyer Expansion Calculator Calculate downstream Mach number and ideal pressure, temperature, and density ratios through a supersonic expansion fan. Shear-Wave Velocity Calculator Estimate shear-wave speed in a material from shear modulus and density, with an optional travel-time scenario. Thermal Conductivity Heat-Flow Calculator Estimate steady one-dimensional conductive heat flow through a slab from conductivity, area, thickness, and temperature difference. Rotational Stiffness Calculator Estimate a linear torsional stiffness and ideal elastic energy from applied torque and angular displacement. Spherical Capacitor Calculator Calculate ideal capacitance and stored energy for two concentric spherical conductors with a specified dielectric. Intrinsic Semiconductor Carrier Concentration Calculator Estimate equilibrium intrinsic carrier concentration from effective density of states, band gap, and temperature. Mixed Air Temperature Calculator Calculate the ideal adiabatic mixed-air temperature from two mass-flow streams, temperatures, and specific heats. Frequency and Period Calculator Calculate frequency, period, angular frequency, and a wavelength-based wave speed from a counted cycle interval. Sensible Heat Calculator Calculate the energy needed to change a sample temperature from its mass, specific heat capacity, and temperature interval. Spring Rate and Natural Frequency Calculator Estimate linear spring rate, stored elastic energy, and ideal small-oscillation frequency from force and deflection. Stress Concentration Factor Calculator Estimate an elastic local peak stress and a simple allowable-stress ratio from nominal stress and an entered Kt factor. Twist Rate Calculator Convert a signed number of revolutions over a length into turns per metre, radians per metre, degrees per millimetre, and pitch. Thrust-to-Weight Ratio Calculator Calculate thrust-to-weight ratio, excess thrust, and an ideal no-drag vertical acceleration estimate from force inputs. Age on Other Planets Calculator Convert an Earth age into planetary years and completed birthdays using the selected planet’s sidereal orbital period. Steady Conduction Heat Transfer Calculator Estimate steady heat-transfer rate and energy through a flat layer from conductivity, area, temperature difference, thickness, and time. Telescope Magnification and Exit Pupil Calculator Calculate visual telescope magnification, exit pupil, and focal ratio from objective and eyepiece dimensions. Preliminary Wind Load Force Calculator Estimate dynamic wind pressure and a drag-based force from air density, wind speed, exposed area, drag coefficient, and an optional exposure factor. Solid Shaft Torsional Size Calculator Estimate the required diameter and torque capacity of a solid circular shaft from torque, allowable shear stress, and a safety factor. Enhancement MOSFET Operating Point Calculator Estimate an ideal n-channel enhancement MOSFET current, region, transconductance, and drain power from the square-law model. BJT Voltage-Divider Bias Calculator Estimate the base, collector, and emitter currents and the Q-point of an NPN transistor using a voltage-divider bias model. Single-Phase Motor Power-Factor Capacitor Calculator Estimate the shunt capacitor needed to move a single-phase inductive load from an entered power factor to a higher target. Ideal-Gas Thermodynamic Process Calculator Compare final state, boundary work, internal-energy change, and heat transfer for an ideal-gas isothermal, isobaric, isochoric, or adiabatic process. True Strain Calculator Calculate logarithmic true strain, engineering strain, stretch ratio, and percentage change from original and final lengths. Shear Modulus from Stress and Strain Calculator Calculate an apparent shear modulus from entered shear stress and dimensionless shear strain. Muzzle Velocity from Projectile Energy Calculator Calculate the ideal exit speed of a projectile or object from its mass and kinetic energy, with momentum and unit conversions shown. kVA to Amperage Calculator Convert apparent power, RMS voltage, and single- or balanced three-phase selection into an estimated line current. MOSFET Threshold Voltage from Operating Point Calculator Estimate an ideal n-channel MOSFET threshold voltage from a measured or specified drain current, square-law parameter, and gate-to-source voltage. AWG Wire Gauge Geometry and Resistance Calculator Convert an American Wire Gauge number into conductor diameter, cross-sectional area, and estimated resistance for a selected material and length. Volts to Electron-Volts Energy Calculator Calculate the energy change in electron-volts and joules from a potential difference and a charge expressed in elementary-charge units. Latitude and Longitude to UTM Converter Convert WGS84 latitude and longitude into a Universal Transverse Mercator zone, latitude band, easting, and northing for locations between 80°S and 84°N. Psychrometric Moist-Air Properties Calculator Estimate saturation pressure, vapor pressure, humidity ratio, dew point, specific volume, and moist-air enthalpy from dry-bulb temperature, relative humidity, and air pressure. Spring Rate Unit Converter Convert a spring stiffness value between newtons per metre, newtons per millimetre, pound-force per inch or foot, kilopounds per inch, kilogram-force per millimetre, and equivalent joules per square metre. Pure Water Density by Temperature Calculator Estimate pure-water density at atmospheric pressure from temperature, then calculate the mass of a chosen water volume and compare an object's density with the water state. Rolling Cylinder Ramp Race Calculator Compare the ideal acceleration, final speed, and travel time of a solid cylinder, cylindrical tube, or thin shell rolling down a ramp from rest. Quarter-Mile Performance Estimate Estimate quarter-mile elapsed time and trap speed from vehicle mass, engine power, and a selected empirical drag-racing correlation, with metric and imperial inputs supported. Water Heating Energy and Time Calculator Estimate the sensible energy, input energy, and heating time for a stated mass of liquid water when the heater power and efficiency are known. Refrigeration Ton to Kilowatt Converter Convert refrigeration capacity in tons of cooling into kilowatts and British thermal units per hour without confusing cooling capacity with electrical input power. SiPM Photon Detection Efficiency Calculator Estimate photon detection efficiency from responsivity, wavelength, gain, optical crosstalk, and afterpulsing using a transparent SiPM measurement relation. Relativistic Bug–Rivet Paradox Calculator Explore length contraction, information-travel time, tip travel, and critical speed ratios in a bounded educational bug–rivet thought experiment. Universe Expansion Scenario Model Integrate a bounded dimensionless scale-factor scenario from present time using matter, radiation, curvature, dark-energy fractions, and a chosen Hubble constant. Actual and Theoretical Yield Calculator Calculate percent yield and the difference between theoretical and recovered product mass from an explicit chemistry experiment. Standard Temperature and Pressure Gas Calculator Compare common standard-state conventions by calculating ideal-gas volume, mass, density, and molar volume for a chosen amount of gas. Newton’s Third-Law Force Pair Calculator Resolve one interaction force into components and return the equal, opposite force on the other body without confusing the pair with forces on one body. SUVAT Constant-Acceleration Calculator Calculate final velocity, displacement, final position, and average velocity for one-dimensional motion with constant acceleration. CNC Machining Speeds and Feeds Calculator Estimate spindle speed and feed rate from cutting speed, tool diameter, flute count, chip load, and a user-entered machine RPM limit. Circular Shaft Torsional Constant Calculator Calculate the polar torsional constant, elastic torsional stiffness, twist, and surface shear stress for a solid circular shaft. Torsional Spring Torque and Energy Calculator Calculate elastic torque, total torque with an entered preload, angular deflection, and stored spring energy for an ideal torsional spring. Rockwell C and Vickers Hardness Estimate Estimate a Rockwell C or Vickers hardness value for the ASTM non-austenitic-steel equation scope, with the material and validity limits kept visible. Earthquake Magnitude and Energy Scenario Calculator Estimate the approximate energy associated with a moment magnitude and compare the energy and amplitude ratios between two magnitudes. Corrosion Thickness-Loss Scenario Calculator Estimate linear material thickness loss from an entered corrosion penetration rate and test how long a component remains above a chosen minimum thickness. Vapor Pressure Deficit Calculator Estimate saturation vapor pressure, actual vapor pressure, and vapor pressure deficit from air temperature and relative humidity using a transparent FAO-style approximation. Horse Weight Estimate Calculator Estimate a horse's body weight from heart-girth circumference and body length using a clearly labeled measurement-based equation and life-stage divisor. Tree Diameter from Circumference Calculator Convert a measured tree circumference into diameter, radius, and common forestry units while keeping the measurement height visible. Tree Age Growth-Factor Estimate Estimate a tree's approximate age from diameter and a user-selected growth factor, with a visible uncertainty band rather than a false exact age. Vegetable Yield Planning Calculator Estimate a garden harvest from growing area, an entered yield density, and the number of planned harvest cycles without pretending every crop or climate has one fixed yield. Trihybrid Cross Probability Calculator Calculate the eight dominant and recessive phenotype probabilities for three independently assorting traits from six parent genotype inputs. Protein Molecular Weight from Sequence Calculator Estimate a protein's average molecular mass from a one-letter amino-acid sequence, accounting for peptide-bond water loss and reporting daltons and kilodaltons. MLVSS Wastewater Solids Calculator Calculate mixed-liquor volatile suspended solids concentration, inert suspended solids, and total volatile solids mass from MLSS, volatile fraction, and basin volume. Horse Gestation Date Range Calculator Estimate average, early-bound, and late-bound foaling dates from a breeding date and explicit horse gestation intervals. Engine Compression Ratio Calculator Calculate swept displacement, total cylinder volume, and nominal static compression ratio from bore, stroke, cylinder count, and clearance volume. Simplified Circuit Breaker Load Estimate Estimate a planning minimum overcurrent-device rating from continuous and noncontinuous loads, then round to a common standard rating. Light-Year Distance and Travel-Time Converter Convert a distance in light-years to metres, kilometres, astronomical units, parsecs, and the corresponding light-travel time. Current-Loop Magnetic Dipole Moment Calculator Calculate the magnetic dipole moment of a multi-turn current loop and its ideal torque and potential energy in a uniform magnetic field. Circular Shaft Torsional Stiffness Calculator Estimate the torsional stiffness, twist torque, and outer-fiber shear stress of a circular shaft from material rigidity and geometry. Watts to Lux Estimate from Luminous Efficacy Estimate illuminance from electrical power, a supplied luminous efficacy, utilization factor, and illuminated area. Buoyancy Experiment Density Calculator Use mass readings in air and while fully submerged to estimate apparent mass loss, buoyant force, displaced volume, and object density. Pendulum Kinetic Energy Calculator Estimate height drop, ideal speed, potential-energy loss, and kinetic-energy gain for a pendulum released from rest at one angle. Earth Curvature Geometry Comparator Compare the exact spherical-surface drop below a local tangent plane with the small-distance approximation and a flat-plane zero-drop reference. Capillary-Tube Pressure-Drop Screening Calculator Estimate single-phase frictional pressure drop, Reynolds number, velocity, and head loss in a small tube from flow, fluid properties, length, diameter, and roughness. Smartphone Projector Lens Geometry Calculator Estimate screen distance, signed magnification, projected image height, and orientation from a thin-lens smartphone projector geometry. Lever Mechanical Advantage Calculator Estimate ideal and efficiency-adjusted mechanical advantage, output force, and work for a simple lever. Sphere Density from Mass and Diameter Calculate the volume, average density, weight, and specific gravity of an ideal sphere from mass and diameter. Air Water-Vapor Mixing Ratio Calculator Calculate water-vapor mixing ratio, mass fractions, and dry-air pressure from vapor and total pressure. Control-Valve Cv Requirement Calculator Compare required and rated liquid valve Cv from target flow, pressure drop, and specific gravity. Impact Test Energy Screening Calculator Estimate impact energy, absorbed energy, average stopping force, momentum, and area-normalized energy in a simplified test scenario. Grams to Moles Chemistry Calculator Convert a measured mass and a supplied molar mass into moles, millimoles, and an estimated count of specified entities. Molecular Weight from Chemical Formula Calculator Parse a chemical formula with element counts and brackets to estimate molar mass, relative molecular mass, and total atoms per formula unit. Moles to Atoms Calculator Convert moles of molecules, formula units, or another specified entity into entity count, individual atom count, and moles of atoms. Percent Solution Concentration Calculator Calculate w/w, w/v, or v/v solution concentration from a solute amount and the total solution amount using matching basis units. Solution Dilution Calculator Use C₁V₁ = C₂V₂ to check an entered stock volume, calculate the stock volume needed for a target concentration, and find the diluent volume. Elliptical Impact Angle Estimator Estimate an acute angle from the measured major and minor axes of an ellipse-shaped impact mark, with explicit forensic limitations. Hardy–Weinberg Equilibrium Calculator Estimate allele frequencies, expected two-allele genotype counts, and a chi-square screening value from observed genotype counts. Projectile Kinetic Energy Calculator Calculate classical kinetic energy and momentum from projectile mass, speed, and a stated count for an educational physics worksheet. DC Resistor Wattage Calculator Solve a single-resistor DC circuit from any selected pair of voltage, current, and resistance values, then show dissipated power and a visible planning margin. Kilograms to Newtons (Mass to Weight) Calculator Convert a mass into gravitational force using an explicitly entered local gravitational acceleration. Normal Stress Calculator Calculate average axial normal stress from an applied force and loaded cross-sectional area. Capacitor Charge and Energy Calculator Calculate stored charge and electrostatic energy from capacitance and voltage for an ideal capacitor. Vertical Rope Tension Calculator Estimate the tension in an ideal vertical rope supporting a mass with a stated vertical acceleration. Ohm's Law Current Calculator Calculate current through an ideal ohmic resistance from voltage and resistance, with power and conductance shown as supporting results. Average Shear Stress Calculator Calculate average shear stress from a shear force and resisting area, with Pa, kPa, and MPa outputs. Wattage to Amperage Calculator Estimate electrical current from real power, voltage, and power factor for a single-phase or balanced three-phase model. Horizontal Projectile Motion Calculator Calculate flight time, horizontal range, and impact speed for an object launched horizontally from a height. Local Sidereal Time Calculator Calculate Julian date, approximate Greenwich mean sidereal time, and local mean sidereal time from a UTC date, time, and longitude. Rain-to-Snow Equivalent Calculator Estimate fresh and settled snow depth from liquid-equivalent precipitation, a chosen snow-to-liquid ratio, and a transparent settling allowance. Flight Cosmic-Radiation Exposure Estimate Estimate cumulative effective dose from an entered average in-flight dose rate, flight duration, number of flights, and optional scenario reduction. Cat Age to Human-Equivalent Years Calculator Estimate a cat's human-equivalent age from completed years and months using a transparent staged age convention and an explicit life-stage band. Cat Pregnancy Date-Range Calculator Estimate early, typical, and late planning dates from a cat breeding or ovulation reference date and editable gestation intervals. Bird Age to Human-Equivalent Years Calculator Map a bird's chronological age onto a user-supplied human reference lifespan while keeping the species lifespan assumption visible. Protein Concentration from A280 Calculator Estimate protein concentration from a corrected 280 nm absorbance, path length, dilution factor, and protein-specific 0.1% extinction coefficient. Wastewater Flow Planning Calculator Estimate average flow, infiltration and inflow allowance, peak design flow, and a simple retention volume from population and entered planning assumptions. Saturated Liquid Ethylene Density Calculator Interpolate a NIST table of saturated-liquid ethylene molar density from 105 K to 160 K and convert it to an approximate mass density. BTU per Hour to Refrigeration Tons Calculator Convert cooling capacity in BTU per hour to refrigeration tons, kilowatts, and daily heat-removal equivalents. Specific Gravity from Density Calculator Calculate specific gravity from a material density and an explicit reference density, with a sample-mass comparison. Particle Speed from Kinetic Energy Calculator Solve the classical non-relativistic kinetic-energy equation for particle speed and momentum from energy and mass. Two-Node Spring Stiffness Matrix Calculator Build the local 2×2 stiffness matrix for a linear spring element and calculate nodal forces, extension, and strain energy. Moist-Air Mixing Calculator Estimate the mixed dry-bulb temperature, humidity ratio, enthalpy, and relative humidity for two adiabatically mixed air streams. Olbers’ Paradox Finite Shell Demonstration Estimate the finite shell contribution and cumulative flux in a simplified uniform-star model to explore why an infinite static universe creates a paradox. Weight on Planets and the Moon How much a mass weighs under each body's surface gravity, in newtons. Friction Force Coulomb friction force from coefficient μ and normal force. Hydraulic Pressure Pressure from an applied force over a piston area, in pascals and kilopascals. Half-Life Remaining Quantity What remains of a decaying sample after a given elapsed time. Percent Concentration (w/w, w/v) Weight/weight or weight/volume percent from solute and total solution. Gas Volume at STP Litres and molecule count for moles of ideal gas at STP. Punnett Square (Single Trait) Offspring genotype odds for a one-gene cross of two parents. Microscope Magnification Total magnification from ocular and objective lenses. CFU per mL (Plate Count) Viable concentration from colonies, plated volume, and dilution. Average Speed Mean travel speed from distance and time, in km/h and m/s. Energy Efficiency Energy efficiency from useful output over total input. Molar Mass Molar mass of a formula with per-element mass breakdown. Buffer pH Buffer pH from pKa and base/acid concentrations. Cell Size from Field of View Mean cell size from microscope field diameter and cell count. Pascal's Hydraulic Lift Output force from input force and two piston areas. Impulse and Momentum Change Impulse, velocity change, and final velocity from force and time. Logistic Population Growth Capped growth from carrying capacity and intrinsic rate. Percent Composition Molar mass and element mass percents from a formula. Decibel Level Comparison Converts an intensity ratio into decibels relative to a reference. Mole Fraction Calculate one component's mole fraction and percentage from its amount and the total amount of substance. Partial Pressure Calculate a component gas's partial pressure from total pressure and its mole fraction. Gibbs Free Energy Change Estimate Gibbs free-energy change from enthalpy change, temperature, and entropy change. Moles to Particles Convert an amount in moles to an estimated number of representative particles using Avogadro's constant. Centripetal Force Calculate the inward radial force needed for an object moving at a stated speed along a circular path. Buoyant Force Calculate the upward buoyant-force magnitude from fluid density, displaced volume, and local gravitational acceleration. Photon Energy Calculate photon energy from wavelength using Planck's constant and the speed of light. Activation Energy from Two Rates Estimate an apparent activation energy from two rate constants measured at different absolute temperatures. Air-Fuel Ratio Calculate the mass ratio of air to fuel and its reciprocal fuel-to-air ratio for a stated mixture. Alligation Mixture Find the masses of a low-concentration and high-concentration material needed to make a target concentration. Arrhenius Equation Estimate a rate constant from a pre-exponential factor, activation energy, and absolute temperature. Atom Economy Calculate the theoretical percentage of reactant mass incorporated into a desired product. Beer-Lambert Law Calculate absorbance, transmittance, and percent transmittance from molar absorptivity, path length, and concentration. Boiling-Point Elevation Estimate the boiling-point increase caused by a dissolved solute using molality and the solvent constant. Molecular-Orbital Bond Order Calculate a simple molecular-orbital bond order from bonding and antibonding electron counts. Weighted Average Atomic Mass Calculate the weighted average mass of a two-isotope mixture from isotope masses and percentage abundances. Weak-Acid Buffer Capacity Estimate the buffer capacity of a monoprotic weak-acid system from total concentration, pKa, and pH. de Broglie Wavelength Calculate the matter-wave wavelength associated with a supplied particle momentum. Electric Field of a Point Charge Calculate the electric-field magnitude at a distance from an ideal point charge in vacuum. Electric Potential of a Point Charge Calculate the electric potential at a distance from an ideal point charge. Magnetic Field of a Straight Current-Carrying Wire Calculate the magnetic-field magnitude around an ideal long straight wire carrying current. Simple Pendulum Frequency Estimate the oscillation frequency of an ideal simple pendulum from its length and local gravity. Ideal LC Resonant Frequency Calculate the natural resonant frequency of an ideal inductor-capacitor circuit. Ideal Rocket Delta-v Estimate ideal rocket velocity change from specific impulse and initial and final mass. Photoelectric Effect Calculate the maximum photoelectron kinetic energy from wavelength and a material work function. Allele Frequency Calculate the frequencies of two alleles from their observed copy counts in a population sample. Daily Light Integral Estimate daily photosynthetic photon delivery from average PPFD and illuminated hours. DNA to mRNA Sequence Transcribe a DNA sequence into an mRNA sequence using an explicit coding or template strand choice. Capacitive Reactance Calculate the magnitude of a capacitor's opposition to sinusoidal AC at a chosen frequency. Inductive Reactance Calculate the magnitude of an inductor's opposition to sinusoidal AC at a chosen frequency. Capacitor Stored Energy Calculate the ideal energy and charge stored by a capacitor at a supplied voltage. Capacitors in Series Find the equivalent capacitance of two or more ideal capacitors connected in series. Parallel Capacitors Find the equivalent capacitance of two or more ideal capacitors connected in parallel. Inductors in Series Find the equivalent inductance of two or more ideal uncoupled inductors connected in series. Inductors in Parallel Find the equivalent inductance of two or more ideal uncoupled inductors connected in parallel. Current Divider Calculate the currents in two parallel resistive branches from total current and branch resistances. Voltage Divider Calculate the output voltage and current of an unloaded two-resistor series divider. RC Circuit Charging Estimate capacitor voltage, charge, and current during ideal charging from a constant-voltage step. Series RLC Impedance Calculate the magnitude, net reactance, and phase angle of an ideal series RLC circuit at one frequency. Source Internal Resistance Calculate terminal voltage and power losses for an ideal source with internal resistance delivering current. Acres Per Hour Calculate an area-completion rate in acres per hour from a nonnegative area and a positive elapsed time. Animal Mortality Rate Calculate an interval mortality rate per 1,000 and as a percentage from deaths and the number surviving at the interval start. Annealing Temperature Quick Screen Estimate a short oligo melting temperature with the educational Wallace count rule, subtract an offset for a screening annealing temperature, and report GC percentage. Bacteria Growth Calculate continuous idealized population growth from an initial population, a positive doubling time, and elapsed hours. Basal Area From Diameter Estimate circular cross-sectional area per stem and in total from a supplied diameter and a safe stem count. Bulb Spacing Area Estimate Estimate the number of equally spaced bulbs for a rectangular bed using a square-grid footprint and a whole-unit ceiling. Cattle Per Acre Calculate a descriptive cattle-per-acre rate from a safe whole-number cattle count and positive acreage. Cell Doubling Time From Observations Estimate an idealized doubling time from positive observed populations, a larger final observation, and elapsed hours. Corn Harvest Density Calculate descriptive harvested corn mass per hectare from an entered mass and harvested area. Dihybrid Cross Punnett Square Calculate genotype and simplified phenotype percentages for a two-locus cross using nine canonical parent genotypes. DNA Concentration Calculate DNA mass concentration from an entered mass and sample volume, with equivalent ng/uL and ug/mL outputs. DNA Copy Number From Mass Estimate the number of double-stranded DNA molecules from mass and a safe whole-number base-pair length. Shannon Diversity Index Calculate descriptive Shannon diversity and evenness from a bounded list of entered species or group counts. Hydroelectric Power Calculate idealized hydraulic and delivered electrical power from entered water flow, hydraulic head, and efficiency. Solar Panel Wattage Calculate idealized instantaneous solar-panel power from entered irradiance, panel area, and conversion efficiency. Wind Turbine Power Calculate idealized kinetic wind power and estimated turbine power from entered air density, swept area, wind speed, and power coefficient. Torque from Force and Lever Arm Calculate the magnitude of torque from a force, lever-arm length, and the angle between them. Angular Momentum of a Point Mass Calculate angular momentum magnitude for a point mass moving tangentially at a stated radius and speed. Rotational Kinetic Energy Calculate the rotational kinetic energy of an ideal rigid body from its moment of inertia and angular speed. Elastic Potential Energy Calculate the elastic potential energy stored in an ideal linear spring from its spring constant and displacement. Gravitational Force Between Two Point Masses Calculate the magnitude of Newtonian gravitational force between two point masses at a stated separation. Escape Velocity Calculate the classical escape velocity at the surface of an ideal spherical body from its mass and radius. Latent Heat Calculate the energy required for a phase change from mass and specific latent heat. Linear Thermal Expansion Calculate length change and final length from initial length, linear expansion coefficient, and temperature change. Coulomb's Law Calculate the magnitude and attraction or repulsion relationship for two point charges at a stated separation. Magnetic Force on a Current-Carrying Wire Calculate the magnetic-force magnitude on a straight current-carrying wire in a uniform magnetic field. Snell's Law Calculate the refracted angle from two refractive indices and an incident angle, including a total-internal-reflection result when appropriate. Thin Lens Equation Calculate image distance and magnification from a signed focal length and positive object distance. Diffraction-Limited Angular Resolution Calculate the Rayleigh diffraction-limit angular resolution of a circular aperture from wavelength and diameter. Stefan-Boltzmann Law Calculate ideal thermal-radiation power from emissivity, radiating area, and absolute temperature. Wien's Displacement Law Calculate the ideal blackbody peak wavelength from absolute temperature. Angular Acceleration Calculate average angular acceleration from initial angular velocity, final angular velocity, and a positive time interval. G-Force from Acceleration Express a supplied acceleration magnitude as a multiple of standard gravity without calculating force in newtons. Stellar Parallax Distance Calculate an astronomical distance from a positive stellar parallax entered in arcseconds, reporting parsecs and light-years. Circular Two-Body Orbital Velocity Calculate the Newtonian relative speed for two positive masses in a circular orbit at a stated center-to-center separation. Special-Relativistic Time Dilation Calculate proper elapsed time from a coordinate-time interval and a subluminal speed using the special-relativistic inertial-clock relation. Empirical Formula Determine an empirical formula from mass percentages for two to twelve supported elements. Molality Calculate solution molality from solute amount and the mass of solvent in kilograms. Freezing-Point Depression Estimate the freezing-point decrease and solution temperature for a dilute ideal solution. Raoult's Law Calculate a volatile solvent mole fraction, ideal solution vapor pressure, and pressure lowering. PPM to Molarity Convert a mass-based ppm concentration into molarity and mass concentration using solution density. Mass-Energy Equivalence (E=mc^2) Calculate the rest energy represented by a mass using the special-relativity equivalence E0 = mc^2. Relativistic Kinetic Energy Calculate kinetic energy from mass and speed as a fraction of the speed of light using the Lorentz factor. Relativistic Velocity Addition Combine two signed collinear subluminal velocities using the special-relativistic velocity-addition formula. Hooke's Law Spring Force Calculate the ideal restoring force and its magnitude from a linear spring constant and signed displacement. Carnot Efficiency Limit Calculate the ideal reversible Carnot efficiency limit from hot- and cold-reservoir temperatures in kelvins. Index of Refraction from Light Speed Calculate a medium's refractive index and light-speed fraction from its supplied light speed. Beat Frequency Calculate the ideal beat frequency produced by two entered frequencies. Doppler Effect Moving Source Calculate the observed frequency and shift for a stationary observer and a one-dimensional moving source in a still medium. Heisenberg Position-Momentum Uncertainty Calculate the minimum momentum uncertainty associated with a positive position uncertainty using the one-dimensional Heisenberg bound. Two-Body Thermal Equilibrium Temperature Calculate the final equilibrium temperature and signed heat transfer for two bodies sharing heat in an isolated constant-specific-heat model. Cyclotron Frequency, Angular Frequency, and Period Calculate the angular frequency, ordinary frequency, and period of a signed charged particle in a positive magnetic field. Malus's Law Polarized Intensity Calculate transmitted intensity and the ideal transmission fraction for linearly polarized light passing through an analyzer at a stated angle. Kepler's Third Law Two-Body Orbital Period Calculate a Newtonian two-body orbital period in seconds and days from semimajor axis and primary and secondary masses. Voltage Drop Calculator Calculate two-conductor voltage drop from current, one-way length, resistance, and source voltage. Wind Chill Calculator Calculate the National Weather Service wind-chill index for Fahrenheit air temperatures and wind speeds. Heat Index Calculator Calculate the National Weather Service Rothfusz heat-index estimate from Fahrenheit temperature and humidity. Dew Point Calculator Estimate dew point from Celsius air temperature and relative humidity with the Magnus approximation. Torque and Horsepower Calculator Convert torque and rotational speed into watts, kilowatts, and mechanical horsepower.

Length Converter Convert metric and international customary lengths, including statute and nautical miles, using defined factors. Weight and Mass Converter Convert kilograms, grams, milligrams, metric tonnes, pounds, ounces, and stones as units of mass. Temperature Converter Convert absolute temperatures among Celsius, Fahrenheit, and Kelvin, with absolute-zero validation. Area Converter Convert square metric and customary units, hectares, and international acres without confusing linear and area factors. Volume Converter Convert liters, milliliters, cubic units, US liquid gallons, and Imperial gallons with explicit gallon definitions. Speed Converter Convert meters per second, kilometers per hour, miles per hour, feet per second, and knots. Angle Converter (Degrees and Radians) Convert angles between degrees and radians. Dimensional Weight and Chargeable Weight Calculator Estimate volumetric shipping weight and choose the larger of actual and dimensional weight using a user-supplied divisor. Acres to Ares Conversion Calculator Convert an area in acres to ares and square metres using an exact metric relationship. Angle Degrees Radians and Turns Converter Convert a degree angle into radians and full turns. Angstroms to Nanometres Converter Convert a length in angstroms to nanometres and metres. Atmospheres to Pascals Converter Convert standard atmospheres to pascals and kilopascals. Bar to PSI Converter Convert pressure in bar to pounds per square inch and kilopascals. Binary to Hexadecimal Converter Convert a nonnegative binary integer into hexadecimal and decimal representations. Bytes Bits and Decimal Storage Converter Convert a byte count into bits, decimal kilobytes, and decimal megabytes. Celsius to Fahrenheit Converter Convert a Celsius temperature to Fahrenheit and Kelvin. Centimetres to Feet and Inches Converter Convert centimetres to total inches and a feet-plus-inches display. Decimal Integer to Hexadecimal Converter Convert a signed whole-number value into hexadecimal notation. Degrees to Radians Converter Convert an angle in degrees to radians and turns. dBm to Watts Converter Convert a power level in dBm to watts and milliwatts. Fuel Economy L/100 km to km/L and MPG Converter Convert metric fuel economy in litres per 100 kilometres to kilometres per litre and US miles per gallon. Knots to Kilometres per Hour Converter Convert speed in nautical knots to kilometres per hour and miles per hour. Kilometres to Miles Converter Convert a distance in kilometres to statute miles and metres. Decimal Inches to Fractional Inches Converter Convert decimal inches to the nearest fraction using a selected denominator. Kelvin to Celsius Converter Convert an absolute temperature in kelvin to Celsius and Fahrenheit. Kilograms to Pounds Converter Convert mass in kilograms to international pounds and grams. Kilopascals to PSI Converter Convert pressure in kilopascals to pounds per square inch and bar. Litres to Cubic Centimetres Converter Convert liquid volume in litres to cubic centimetres and millilitres. Acres to Hectares Converter Convert international acres into hectares and square metres for land-area planning. Ares to Hectares Converter Convert ares into hectares and square metres using the metric land-area relationship. CCF to Gallons Converter Convert hundred cubic feet of gas or water volume into cubic feet, US gallons, and litres. CCF to Therms Calculator Estimate natural-gas energy in therms and kilowatt-hours from CCF using an explicit heat-content input. Crore to Lakh Converter Convert a value expressed in crores into lakhs and the underlying count of units. Crore to Million Converter Convert crores into millions and billions while keeping the underlying count visible. Million to Lakh Converter Convert millions into lakhs and crores for comparing international and South Asian number formats. Gaj to Square-Yard Converter Convert a regional gaj area into square yards, square feet, and square metres using a visible local factor. Katha to Square-Feet Converter Convert katha into square feet, square metres, and acres with a user-supplied regional katha factor. Mesh to Micron Opening Converter Estimate sieve pitch and opening size from mesh count and an explicit wire diameter. PPM to Milligrams per Litre Converter Convert a dilute mass concentration in ppm into mg/L and g/L using solution density. Price per Litre to Price per Gallon Converter Convert a unit price per litre into a price per US or imperial gallon without changing the currency. Paper Quantity and Ream Calculator Estimate sheets and reams from page count, copies, print sides, and a visible waste allowance. Pixels to Inches Converter Convert a pixel dimension into inches and centimetres from an explicit pixels-per-inch resolution. Pixels to em and rem Converter Convert a pixel value into em and rem units from the relevant parent and root font sizes. Drawing Scale Converter Convert a drawing length to a real length or reverse it using a clear 1-to-N scale denominator. Natural Gas Volume and Energy Converter Convert CCF, therms, cubic metres, and kilowatt-hours using explicit regional heat-content assumptions. Gallons to Mass and Tons Calculator Convert a liquid volume into kilograms and US short or metric tonnes from density and gallon definition. Cubic Yards to Tons Calculator Estimate material mass from cubic yards, bulk density, and a visible waste allowance in US short and metric tonnes. Grams to Fluid Ounces Converter Convert mass into millilitres and US or imperial fluid ounces using an explicit material density. Astronomical Unit Converter Convert astronomical units to metres, kilometres, and miles using the exact SI-defined astronomical unit. Barometric Pressure Unit Converter Convert a pressure reading in hectopascals into pascals, kilopascals, millimetres of mercury, inches of mercury, and psi. Billion to Trillion Converter Convert a decimal count expressed in billions into trillions, millions, and the underlying absolute count. Binary to Octal Converter Convert a nonnegative binary integer into decimal, octal, and hexadecimal representations. Cubic Centimetres to Millilitres Converter Convert cubic centimetres into millilitres, litres, and cubic metres using the exact volume equivalence. Celsius Temperature Converter Convert a Celsius temperature into Fahrenheit, kelvin, and Rankine while keeping absolute-zero validation visible. Centimetres to Kilometres Converter Convert a length in centimetres into metres, kilometres, millimetres, and inches. US Cups to Pints Converter Convert US customary cups into US pints, fluid ounces, quarts, and gallons with the serving-volume convention stated. Day to Time-Unit Converter Convert days into hours, minutes, seconds, and weeks using a fixed 24-hour day. Decagram to Gram Converter Convert decagrams into grams, kilograms, milligrams, and pounds using SI mass prefixes and the international pound. Decimal Degrees to DMS Converter Convert signed decimal degrees into degree, arcminute, arcsecond, and total-arcsecond components. Hectares to Acres Converter Convert hectares into square metres, square kilometres, international acres, and square feet. Knots to Miles per Hour Converter Convert nautical speed in knots into international miles per hour, kilometres per hour, and metres per second. Kilograms to Stones Converter Convert kilograms into UK stones, pounds, grams, and tonnes using the international avoirdupois pound. Kilobytes to Megabytes Converter Convert decimal kilobytes into bytes, megabytes, gigabytes, and binary mebibytes with the convention shown. Kilopascals to Atmospheres Converter Convert kilopascals into standard atmospheres, pascals, psi, torr, and millimetres of mercury. Litres to Centilitres Converter Convert litres into centilitres, millilitres, cubic centimetres, and cubic metres. Micrograms to Milligrams Converter Convert micrograms into milligrams, grams, nanograms, and kilograms while keeping SI prefixes explicit. Minutes to Decimal Time Converter Convert a duration in minutes into decimal hours, decimal days, seconds, and a readable hours-and-minutes value. Light-Year Distance Converter Convert light-years into kilometres, metres, astronomical units, and international miles using light speed and a Julian year. Acreage from Length and Width Calculate land area from rectangular dimensions and display the result in square feet, acres, and hectares. Binary and Decimal Base Converter Convert a nonnegative whole number between binary notation and decimal notation while keeping every bit visible. Hex Color to RGB and HSL Converter Decode a three-, six-, or eight-digit hexadecimal color into RGB, HSL, alpha, and relative luminance values. Cycles per Second and RPM Converter Convert a repeating rate between cycles per second, hertz, and revolutions per minute, then show the period. Cubic Centimeters to Grams Converter Convert a measured volume in cubic centimeters to mass when the material density is known. Cubic Feet to Pounds by Density Estimate material mass in pounds from cubic feet, density, and an optional waste or handling allowance. Land Cent to Square Meter Converter Convert the land-area unit cent to square meters, square feet, and acres using the one-cent-per-hundredth-acre convention. CGS and SI Unit Converter Convert compatible length, mass, force, and energy quantities between common CGS and SI units. Atmospheres Pressure Converter Convert standard atmospheres into pascals, kilopascals, bar, psi, and millimeters of mercury. Bar Gauge to PSIG Converter Convert a gauge pressure in bar to psig, absolute psi, and gauge kilopascals using an explicit atmospheric-pressure setting. Centimeters to Inches Converter Convert centimetres into international inches and companion metric and imperial length units. Acres to Square Feet Converter Convert international acres into square feet, square metres, hectares, and square yards with the unit basis stated. SCFM to SI Flow Converter Convert standard cubic feet per minute into cubic metres per second, cubic metres per hour, and litres per second. Pounds per Minute Flow Converter Convert mass flow in pounds per minute into kilograms per second, kilograms per hour, grams per second, and pounds per hour. Carat Weight Conversion Calculator Convert a gemstone mass between metric carats, points, grams, milligrams, and avoirdupois ounces without confusing carat weight with gold purity. Mbps to Gbps and GB/s Converter Convert megabits per second into gigabits per second, megabytes per second, gigabytes per second, and bits per second using decimal network units. KSI to MPa Pressure Converter Convert pressure in kilopounds per square inch into megapascals, psi, pascals, and gigapascals with explicit unit relationships. mmol/L to mg/dL Calculator Convert a selected laboratory analyte from mmol/L to mg/dL using its molecular weight, with a reverse-conversion check shown beside the answer. Drops to Milliliters Converter Convert a counted number of drops to milliliters, liters, and microliters using the measured drop volume for the actual dispenser. Decimal to Octal Converter Convert a safe-range decimal integer to prefixed octal and binary notation while preserving negative values and showing the digit count. Cents to Dollars Converter Convert a nonnegative number of US cents into dollars, whole dollars, and remaining cents without applying exchange rates. Days to Months Duration Converter Convert elapsed days to months and years using an average Gregorian, 30-day billing, or 365-day-year convention. Hours to Years Duration Converter Convert elapsed hours to years, 24-hour days, and minutes using an explicit hours-per-year convention. Euro Cents to Euros Converter Convert euro cents into euros, whole euros, and the remaining cent component without applying a foreign-exchange rate. Cubic Centimetres to US Fluid Ounces Converter Convert cubic centimetres into US fluid ounces, millilitres, US cups, and litres while keeping volume ounces separate from mass ounces. Numbers to Words Converter Convert whole numbers from zero through 999,999,999 into canonical English words, or parse those words back into a decimal integer. Pressure Unit Converter Convert pressure among pascals, kilopascals, megapascals, bar, standard atmospheres, pounds per square inch, and millimeters of mercury. Energy Unit Converter Convert joules, kilojoules, megajoules, watt-hours, kilowatt-hours, calories, kilocalories, and British thermal units. Power Unit Converter Convert watts, kilowatts, megawatts, mechanical horsepower, and British thermal units per hour. Force Unit Converter Convert newtons, kilonewtons, pounds-force, and kilogram-force through a shared SI base. Frequency Unit Converter Convert hertz, kilohertz, megahertz, gigahertz, and revolutions per minute using cycles per second as the base. Torque Unit Converter Convert newton-meters, kilonewton-meters, pound-feet, pound-inches, kilogram-force meters, and kilogram-force centimeters. Capacitance Unit Converter Convert capacitance values among farads and common SI-prefixed units. Decimal Degrees and DMS Converter Convert a signed decimal-degree coordinate to degrees-minutes-seconds or convert DMS back to decimal degrees. Density Unit Converter Convert density values among common SI and mass-volume units. Custom-Rate Currency Converter Convert an amount with a rate you supply instead of silently using stale or unverified live exchange data. Shoe Size Conversion Convert an approximate shoe size among US men's, US women's, UK, EU, and Japanese length systems.

Travel Fuel Cost Estimator Estimate fuel needed and trip cost from distance, consumption, and fuel price, with explicit units. Weekly Budget Planner Split a total budget evenly across a whole number of weeks to plan weekly spending. Tip and Bill Split Add a tip percentage and split the total evenly across diners. Recipe Scaler Scale any ingredient quantity between serving sizes. Unit Price Comparer Compare two pack prices by cost per unit weight or volume. Paint Estimator Gallons needed from paintable area, coats, and coverage per gallon. Running Pace and Speed Pace per kilometre or mile plus average speed from distance and time. Concrete Bags Estimator Bags of premix from slab volume and per-bag yield. Mulch and Soil Volume Cubic yards from bed area and depth, plus bag count. Fuel Cost Estimate Estimate fuel volume and cost from trip distance, fuel economy, and the price you enter. Tip, Tax, and Bill Split Calculator Calculate an entered tip and tax amount, total bill, and equal share per person. Audiobook Playback Time Calculator Calculate adjusted listening time and time saved when playback speed changes. Battery Charge Time Calculator Estimate charging time from battery capacity, charger current, and a charging-efficiency allowance. Flight Carbon Dioxide Estimate Estimate flight carbon dioxide from distance, fuel use, emission factor, and passenger count supplied by the user. Appliance Energy Cost Calculator Estimate energy use and cost from appliance power, operating time, days, and an entered electricity price. Classroom Space per Person Calculator Calculate floor area per person and total capacity from room dimensions and a chosen spacing allowance. Bathroom Mirror Width Calculator Calculate a maximum mirror width from vanity width and selected side clearances, plus mirror area from height. Balloon Arch Quantity Calculator Estimate balloon count from an arch length, center-to-center balloon spacing, and an optional planning allowance. Bath Versus Shower Water Calculator Compare weekly water use from showers and baths using explicit duration, flow, frequency, and bath-volume assumptions. Rectangular Bag Capacity Calculator Calculate internal volume and approximate litre capacity for a rectangular bag from dimensions and fill percentage. Antipode Coordinate Calculator Calculate the opposite point on Earth from a latitude and longitude using a spherical coordinate convention. Binge-Watching Time Calculator Calculate total viewing time and adjusted time at a selected playback speed from episode count and duration. Travel Cost per Distance Calculator Calculate fuel cost per kilometre and total trip fuel cost from fuel economy, fuel price, and distance. Cost per Minute Calculator Calculate cost per minute and total cost from a charge and the duration it covers. Aquarium Volume Calculator Calculate rectangular aquarium volume in litres and usable water volume from dimensions and a fill percentage. Cleaning Service Cost Calculator Estimate cleaning cost from area, price per area unit, visit count, and an optional supply allowance. Boat Speed and Travel Time Calculator Calculate average boat speed and travel time from distance and the other selected time or speed input. Bed Area and Linen Size Calculator Calculate rectangular bed area and a minimum mattress-covering size from bed length, width, and side allowance. Commute Time and Cost Calculator Estimate commute time and fuel cost from one-way distance, trips per week, speed, fuel economy, and fuel price. Bean Bag Filling Volume Calculator Estimate fill volume for an ellipsoid-like bean bag from its three overall dimensions and a selected fill fraction. Cubic-Metre Shipping Volume Calculator Calculate total shipment volume in cubic metres from rectangular package dimensions and quantity. Circle Skirt Fabric Calculator Estimate the inner radius, cut radius, and fabric area for a full-, half-, or quarter-circle skirt from waist, length, and allowance inputs. Clay Shrinkage Calculator Estimate dried or fired clay dimensions and volume change from wet dimensions and a stated linear shrinkage percentage. Cross-Stitch Fabric Size Calculator Convert stitch counts and fabric count into stitched dimensions, cut dimensions, and approximate fabric area with a visible margin. Curtain Panel Quantity Calculator Estimate finished panel count, total cut width, and fabric area from a window width, fullness ratio, panel width, and drop. Fuel Distance Calculator Estimate travel distance from fuel volume and vehicle consumption, with the result shown in kilometres, miles, and kilometres per litre. Carpool Cost Calculator Estimate shared trip distance, fuel use, total fuel cost, and equal cost per passenger from route, schedule, vehicle consumption, and fuel price. Rectangular Container Loading Calculator Estimate how many identical rectangular boxes fit in a rectangular container for one selected axis-aligned orientation, with axis counts and volume utilization. Pallet Packing Layout Calculator Compare two axis-aligned package orientations on a rectangular pallet and estimate per-layer capacity, footprint utilization, and total boxes across layers. TV Mounting Height Geometry Calculator Estimate a screen's width, height, top, bottom, center position, and viewing angle from diagonal size, aspect ratio, eye height, and viewing distance. Garbage Bag Size Planner Estimate the minimum flat width and length of a liner for a rectangular bin, then add visible fitting allowances before checking a product label. Picture Frame and Mat Size Calculator Calculate a mat outer size, frame outer size, visible artwork area, mat area, and frame perimeter from artwork and border measurements. Paper Thickness and Stack Height Calculator Infer sheet caliper from a measured paper stack and project the height, inches, and sheets-per-inch for another sheet count. Paper Sheet Mass and Ream Weight Calculator Calculate the mass of paper sheets and a 500-sheet ream from grammage, sheet dimensions, and quantity. Quilt Binding Strip Calculator Estimate binding length, whole strips, fabric cut width, and unused strip length from quilt dimensions and a visible joining allowance. Desk Height Fit Calculator Compare entered seated and standing elbow heights with task offsets and desk adjustment ranges without claiming one universal ergonomic height. Diaper Supply Planner Estimate disposable diaper units and packs for a stated number of babies, days, daily changes, buffer, and package size. Cordwood Volume Calculator Convert a rectangular stacked firewood pile into cubic feet, standard cord equivalents, and an entered purchase estimate. Helium Balloon Lift and Quantity Calculator Estimate the lift of one spherical helium balloon and the number needed for a payload after accounting for envelope mass and a visible planning margin. Meeting Cost Calculator Estimate the direct and loaded cost of a meeting from participant time, preparation time, a local hourly rate, and an explicit overhead percentage. Microwave Wattage Time Adjustment Calculator Scale a package or recipe heating time between two microwave power ratings while keeping the label-time assumption visible. Recessed Lighting Layout Calculator Estimate a regular recessed-light layout from room dimensions, a maximum spacing, edge margin, target illuminance, fixture lumens, and utilization assumptions. Shower Water and Heating Cost Calculator Estimate shower water volume, heating energy, water cost, and energy cost from flow, duration, temperatures, efficiency, and local prices. Wheel Offset and Backspacing Calculator Convert measured wheel backspacing and advertised width into the approximate wheel offset, centerline, overall width, and outboard spacing. Winch Line Pull Planning Calculator Estimate the line pull for moving a mass up a slope from grade, rolling resistance, line efficiency, and a visible safety factor. Crosswind and Headwind Component Calculator Resolve a wind speed into runway-relative crosswind and headwind or tailwind components using a selectable speed unit. Novel Writing Pace Calculator Plan the daily writing pace needed to reach a word-count goal and compare it with a steady entered pace over the remaining days. Lawn Mowing Cost Scenario Calculator Estimate productive mowing time, total visit time, per-visit cost, and seasonal cost from lawn area, mower productivity, user-entered rates, and visit count. Pet-Sitting Visit Cost Scenario Calculator Estimate a pet-sitting invoice from visits, visit duration, base rate, extra-pet fees, travel fees, and one-time charges without claiming a universal local rate. Dog Crate Internal Size Planner Plan minimum internal crate dimensions from a dog's measured body length, standing height, turning diameter, and explicit comfort clearances. Dog Harness Measurement Planner Turn a dog's chest girth, neck girth, and back length into transparent measurement targets with user-entered fit clearances before comparing a manufacturer's size chart. Rabbit Enclosure Space Check Calculator Compare a rabbit enclosure's available floor area and height with visitor-entered welfare baselines and an additional-rabbit allowance. Aquatic Turtle Tank Volume Planner Estimate minimum water volume, litres, and water depth from shell length, turtle count, and editable care-rule factors. Metric Ring Size Planner Convert a measured inner circumference into diameter, inches, and an ISO-style numeric ring-size reference without hiding regional sizing differences. Shoelace Length Planning Calculator Estimate lace length from eyelet pairs, eyelet spacing, across-shoe width, lacing style, and the total allowance needed for tying. Pool Salt Addition Planner Estimate the mass of salt needed to move a pool from a measured concentration to a target concentration using litres, cubic metres, or US gallons. Reading Speed and Study Pace Calculator Calculate words per minute from a timed reading sample and estimate words, pages, or minutes for a study session using that measured pace. Cash Weight Estimator Estimate the total mass, face value, and value density of repeated cash items from a user-entered count, denomination, and unit mass. Data Usage Budget Calculator Project total mobile or broadband data use from average daily usage, active days, an overhead allowance, and a plan limit in the selected data unit. Energy Use Intensity (EUI) Calculator Calculate a building’s annual energy use intensity from total annual energy, floor area, and globally usable energy and area units. Diamond Dimension Weight Estimator Estimate diamond carat weight from shape, dimensions, and an optional proportion adjustment, with clear distinction between planning weight and a laboratory measurement. Traffic Density and Flow Calculator Estimate vehicles per kilometre, per-lane density, flow per lane, and average spacing from a road segment observation. Tables Needed for Guests Calculator Calculate how many identical tables are needed for a guest count, plus seats provided, unused seats, and occupancy. NATO Phonetic Alphabet Encoder and Decoder Encode letters into the international NATO spelling alphabet or decode official code words back into text. Rat Cage Size and Space Check Calculator Compare a rat enclosure’s usable floor area and clear height with an entered welfare baseline for a specified number of rats. Amount in Words Calculator Turn a numeric amount into readable English currency words for supported international currencies, including major and minor units, with a clear warning for formal documents. Density-Based Freight Class Planning Calculator Estimate shipment density and the density-based NMFC planning class from package dimensions and total weight, with the classification boundary kept visible. Generator Wattage Planning Calculator Estimate a generator’s planning wattage and apparent-power requirement from continuous load, starting surge, overlap, reserve, and power factor. Hot-Tub Operating Cost Calculator Estimate hot-tub heating, pump, refill, recurring electricity, and first-fill costs from your equipment and local prices. Fabric Yardage and Cutting-Length Calculator Estimate fabric length for repeated rectangular pieces from piece dimensions, count, fabric width, and an explicit waste allowance. Blind and Shade Size Planner Plan an inside- or outside-mount blind size from opening measurements, depth, overlap, and mounting extensions without applying hidden manufacturer deductions. Pomodoro Focus Schedule Planner Plan focus sessions, short breaks, long-break placement, preparation, and wrap-up time with an explicit schedule rather than a fixed timer guess. D&D Money Conversion Calculator Convert copper, silver, electrum, gold, and platinum pieces into a common copper value and a normalized purse display. 5e Encounter Difficulty Calculator Estimate a fifth-edition 2014 encounter's adjusted XP and compare it with the party's easy, medium, hard, and deadly thresholds. Flag Size and Proportion Planner Plan a rectangular flag's fly length, face area, pole position, and remaining pole using a chosen hoist-to-fly ratio. Flooring Tiles Estimator Tiles needed for a floor area from tile size, plus a buy quantity with waste allowance. Sleep Cycle Wake-Up Time Wake-up time from a bedtime plus a whole number of 90-minute sleep cycles. Wallpaper Rolls Strips and rolls needed from wall size and roll size. Fence Boards Pickets needed for a run from board width and gap. Laundry Loads per Bottle Exact and whole wash loads from bottle size and dose. Pet Food Days Days and weeks one bag lasts at a fixed daily ration. Weekly Screen Time Weekly minutes and hours from average daily screen time. Formula Scoops Scoops of powdered formula from fluid ounces and scoops per ounce. Board Foot Calculate lumber volume in board feet from thickness, width, and length in customary dimensions. Drywall Panel Estimate Estimate the number of drywall panels from wall area, openings, panel size, and an entered waste allowance. Hollow Pipe Volume Calculate the internal volume of a straight hollow circular pipe from its diameters and length. Roof Pitch Calculate roof pitch percentage, slope angle, and rafter length from rise and horizontal run. Idling Fuel Consumption Estimate fuel used and fuel cost from an entered idle consumption rate and duration. Lighting Level Estimate average illuminance from lumens per fixture, fixture count, and illuminated area. Square Footage Calculator Calculate area for rectangles, circles, triangles, and trapezoids, with optional material cost. BTU Room Sizing Estimate Estimate room heating or cooling capacity with a visible area, ceiling, insulation, climate, and occupancy heuristic. Golf Handicap Differential Estimate Estimate a simplified 20-score handicap index from scores, course rating, slope, and PCC. Roofing Materials Estimate Estimate sloped roof area, roofing squares, and nominal bundles from a rectangular plan, pitch, and waste. Gravel and Aggregate Estimate Estimate gravel volume and mass from footprint, depth, waste, and bulk density. Bra Size Estimate Estimate a regional bra band and cup size from underbust and bust measurements. Electricity Use and Cost Calculator Estimate energy use and electricity cost from appliance power, hours, days, and an entered rate. Gas Mileage Calculator Calculate distance, fuel economy, fuel cost, and cost per distance from odometer and refueling readings. Stair Geometry Calculator Estimate riser count, actual riser height, tread count, total run, and stair angle from basic dimensions. Tire Size Comparison Calculate tire section height and overall diameter, then compare diameter and indicated-speed effects.

Recipe Quantity Scaler Scale one ingredient quantity from an original serving count to a new serving count. Alcohol by Volume Calculator Calculate alcohol by volume from pure alcohol volume and total beverage volume. Baker’s Percentage Calculator Express an ingredient mass as a percentage of flour mass for recipe formulation. Coffee-to-Water Ratio Calculator Calculate coffee strength as a water-to-coffee ratio and coffee’s percentage of the combined brew mass. Brine Concentration Calculator Calculate salt concentration by mass from salt and water amounts. Alcohol Dilution Calculator Calculate final mixture volume and added diluent when a stronger beverage is diluted to a target concentration. Cake Serving Calculator Estimate servings from a rectangular cake area and a selected area per serving. Cake Pan Batter Scaling Calculator Scale batter quantity from one round cake pan diameter to another using pan area. Barbecue Food Quantity Calculator Estimate food mass for a barbecue gathering from adult and child guests, portions, and a waste allowance. Bread Spread Quantity Calculator Estimate spread quantity for a number of bread slices with a per-slice amount and an optional allowance. Pizza Area and Topping Calculator Calculate pizza area, area per slice, and topping mass from diameter, slice count, and topping density. Barbecue Grill Area Calculator Estimate minimum cooking-surface area from guest count, area per guest, and a planning allowance. Pancake Recipe Scaling Calculator Scale flour, milk, eggs, and oil amounts from a base serving count to a target number of servings. Homemade Sports Drink Ingredient Calculator Calculate water, sugar, and salt quantities from batch volume and explicit ingredient concentrations. Rice Water Quantity Calculator Calculate water quantity from rice amount and an explicit water-to-rice ratio. Tea Brewing Quantity Calculator Calculate tea leaves and water from serving count and explicit per-serving brewing quantities. Turkey Quantity Calculator Estimate turkey mass from guest count, serving mass per guest, and a planning allowance. Party Drink Volume Calculator Estimate beverage volume and containers from guest count, drinks per guest, serving size, and a planning allowance. DIY Sports Drink Batch Calculator Scale water, sugar, and salt quantities for a visitor-entered homemade sports-drink batch. Bacon Cure Ingredient Scaling Calculator Scale entered salt, sugar, and spice percentages to a selected meat mass for a recipe worksheet. Cooking Volume Measurement Converter Convert common kitchen volume measures between US cups, tablespoons, teaspoons, fluid ounces, milliliters, and liters. Cups to Pounds Ingredient Calculator Estimate an ingredient mass in pounds from cups when you supply that ingredient's grams-per-cup density. Dry to Cooked Pasta Yield Calculator Estimate cooked pasta quantity from dry pasta weight using an adjustable yield factor. Fresh to Dried Herb Conversion Calculator Convert fresh herb volume to a dried-herb estimate with an adjustable strength ratio. Garlic Clove, Gram, and Teaspoon Converter Estimate minced garlic weight and volume from a clove count using explicit per-clove assumptions. Grams to Cups Ingredient Calculator Estimate ingredient volume in cups from grams when you provide grams per cup for that ingredient. Grams to Tablespoons Ingredient Calculator Estimate tablespoons from grams with a user-supplied grams-per-tablespoon density. Grams to Teaspoons Ingredient Calculator Estimate teaspoons from grams with a user-supplied grams-per-teaspoon density. Milliliters to Grams Ingredient Calculator Estimate food mass in grams from milliliters using the ingredient's density in grams per milliliter. Oil to Butter Baking Substitution Calculator Estimate the oil volume used when replacing butter in a recipe with an adjustable butter-to-oil substitution factor. Popcorn Kernel to Popped Volume Calculator Estimate popped popcorn volume and servings from kernel volume using an adjustable expansion factor. Pounds to Cups Ingredient Calculator Estimate ingredient volume in cups from pounds using the ingredient's grams-per-cup density. Salad Calories Scenario Calculator Add ingredient calorie estimates and divide the total across salad servings without assuming a specific food database value. Self-Rising Flour Substitute Calculator Calculate baking powder and salt additions for a specified amount of all-purpose flour. Steak Cooking Time Planning Calculator Estimate a starting cooking time from steak thickness, cooking method, and desired doneness using an adjustable time factor. Turkey Cooking Time Range Calculator Estimate a planning time range from turkey weight and whether the bird is stuffed, then defer to a thermometer and local food-safety guidance. Turkey Defrost Time Calculator Estimate refrigerator or cold-water thawing time from turkey weight and state the cold-water change interval. Uncooked to Cooked Rice Yield Calculator Estimate cooked rice volume and servings from dry rice volume using an adjustable water-absorption yield factor. Fresh, Active-Dry, and Instant Yeast Converter Convert a yeast amount between fresh cake yeast, active dry yeast, and instant yeast using transparent standard ratios. Caffeine Remaining Over Time Calculator Estimate caffeine remaining after a chosen number of hours using an adjustable half-life assumption. Sourdough Hydration Calculator Calculate total flour, total water, dough hydration, and starter contributions for a sourdough formula. Taco Bar Quantity Calculator Estimate tacos, shell packs, filling mass, and combined topping mass for a taco bar from guests, portions, and a visible allowance. Pizza Party Quantity Calculator Estimate planned slices, whole pizzas, served slices, and remaining slices from guests, portions, pizza size by slices, and an extra allowance. Mashed Potato Ingredient Calculator Scale raw potatoes, butter, and milk for a guest count from explicit per-person and per-kilogram recipe ratios. Chilled Drink Ice Calculator Estimate the ice mass needed to cool a water-like drink to a target temperature using an explicit energy-balance model. Priming Sugar Quantity Calculator Estimate a brewing priming-sugar mass from batch volume, target and residual carbonation, and an explicit sugar-yield factor. Ham Quantity per Person Calculator Estimate ham purchase mass from guests, edible serving mass, edible fraction, and a visible leftovers allowance. Beer Pong Supply Planner Plan cups, beverage volume, and replacement balls for a beer-pong session from the number of games and the visible setup assumptions. Wedding Beverage Quantity Planner Estimate alcoholic beverage servings, bottles, and non-alcoholic water servings for an event using explicit guest, duration, and serving assumptions. Ice-Cream Tub Quantity Planner Estimate total ice-cream volume, scoops, and tubs from guests, scoop size, an allowance, and the container size you can buy. Emergency Food Reserve Planner Estimate packaged-food units and total energy for a household reserve from people, days, a chosen daily planning value, and a buffer. Liquid Cooling Time Calculator Estimate a liquid temperature after a time interval, the time to a target temperature, and heat removed using a Newton-cooling model. Salt Dough Recipe Scaling Calculator Scale a craft salt-dough ratio for any flour amount, batch count, and entered salt or water parts while keeping all ingredients in the same measuring unit. Butter Measurement Conversion Calculator Convert butter measured in North American sticks into cups, tablespoons, teaspoons, grams, ounces, and pounds while keeping the regional stick convention visible. Cold Brew Concentrate Ratio Calculator Plan coffee, brew water, concentrate, and dilution water for a cold-brew batch from a finished volume, ratio, and measured yield assumption. Coffee Carbon Footprint Scenario Calculator Estimate a coffee serving or batch footprint from transparent production, transport, packaging, brewing-energy, electricity, and waste factors that you can replace with local data. Pizza Size and Value Comparison Calculator Compare pizza orders by circular area, total price, price per area, and the area advantage of one order over another. Molecular Sulfur Dioxide from pH Calculator Estimate molecular sulfur dioxide from free sulfur dioxide, pH, and an explicit dissociation constant for a simplified acid-equilibrium model. Chocolate Nutrition Scaling Calculator Scale calories, fat, carbohydrate, sugar, and protein from a chocolate nutrition label to a chosen serving count and serving mass. Ham Cooking Time Planning Calculator Estimate a ham cooking-time range from weight and an explicit product-specific time rate, then add a rest period and keep the thermometer check visible. Egg Boiling Time Physics Calculator Estimate egg heating time from mass, starting temperature, water temperature, and a selected center-temperature target. Coffee Caffeine Intake Scenario Calculator Compare planned coffee servings with a visitor-entered daily caffeine limit and a transparent body-weight sensitivity scenario. Coffee Add-On Nutrition Scenario Calculator Estimate caffeine, added sugar, milk, creamer, and total drink calories from a coffee recipe using visitor-supplied label values. Pizza Bake-Time Physics Calculator Estimate pizza bake time from dough thickness, oven temperature, baking surface, and a transparent topping-water allowance. Holiday Meal Calories and Activity Scenario Calculator Add serving calories for a holiday meal, calculate the meal total and per-diner average, and explore an explicit activity-time scenario. Turkey Thawing Time Calculator Estimate refrigerator and cold-water thawing time from turkey weight, with a selected method and food-safety boundaries. Sodium in Salt Calculator Estimate sodium from a salt mass and sodium-chloride purity using reference atomic weights, with outputs for sodium, chloride, and sodium per 100 grams of product. Thanksgiving Meal Planner Estimate turkey weight, kilograms, side-dish servings, and the number of side dishes for a holiday meal with planned leftovers.