Flag Size and Proportion Planner

What the flag planner calculates

The tool calculates the long edge, or fly, from the short edge, or hoist, and a chosen fly-to-hoist ratio. It also calculates rectangular face area, the top of the flag above the pole base, the pole left above the flag, and the hoist as a percentage of pole height.

Every length must use the same unit. If the hoist is in metres, the pole and clearance must also be in metres. The calculator does not convert units because mixing units silently would make a neat-looking but incorrect installation plan.

The ratio formula

The fly-to-hoist ratio is fly divided by hoist. Rearranging gives fly = hoist × ratio. With a 1-unit hoist and a 1.9 ratio, the fly is 1.9 units.

Ratios vary by flag, banner, purpose, and specification. The input is therefore editable and named rather than hidden behind a country-specific default. The result describes the chosen geometry, not a universal legal dimension.

Area and material planning

A rectangular face has area equal to hoist multiplied by fly. In the example, 1 × 1.9 gives 1.9 square units. This is a flat face estimate before adding hems, seams, pockets, overlaps, reinforcement, or waste.

For material purchasing, keep a separate allowance for construction details. A fabric supplier may quote usable width, roll direction, and cut layout that change the amount of material needed even when the face area is correct.

Placing a flag on a pole

The bottom clearance input describes the distance from the pole base to the bottom of the flag. Adding the clearance and hoist gives the top height. Subtracting that top height from the pole height gives the pole remaining above the flag.

The handler rejects a pole that is too short for the entered clearance and hoist. This prevents a negative remaining height from being presented as a plausible result, but it does not decide whether the chosen clearance is appropriate for a public space or a particular mounting system.

Official proportions versus general planning

Some national flags have official proportions and display rules. The U.S. flag specification, for example, defines proportions and detailed elements for that flag. Those rules should not be applied to a different national flag, a private banner, or a decorative sign without checking the relevant authority.

This page uses a general ratio field so visitors can enter the specification that belongs to their project. Its source list includes an official U.S. example as a reference for why named proportions matter, not as a worldwide default.

Installation and wind safety

Geometry does not tell you whether a pole, bracket, rope, fabric, or anchor can withstand wind. A large rectangular flag can exert substantial force, and the risk depends on material, exposure, mounting, maintenance, and local conditions.

For a real outdoor installation, ask a qualified supplier or structural professional to review the pole, fasteners, foundation, and operating conditions. Check local property, road, event, accessibility, and safety rules before placing the flag.

Changing one assumption at a time

If the hoist is doubled while the ratio stays fixed, both fly and area change predictably. If only the ratio changes, the hoist stays fixed while the fly and area move. Running one change at a time helps identify whether the design issue is the panel size or the proportion.

The pole-share result is a separate planning signal. A flag can have a reasonable face ratio but still sit too high, too low, or too close to another object for the intended site.

Limitations and FAQs

Does the tool choose a national flag's legal dimensions? No. Does it calculate wind loading? No. Does area include seams and hems? No. Can I use feet, centimetres, or metres? Yes, as long as every length uses the same unit. Why is the top height clearance plus hoist? The model assumes the hoist runs upward from the bottom clearance; a different mounting orientation needs a different layout model.