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Air Changes per Hour Calculator — result sheet
Calculate air changes per hour from room volume and average ventilation flow, with metric and cubic-foot outputs.
Inputs used
Results
Visual chart
Breakdown
Calculation steps
Returned data table
Formula and methodology
Formula: ACH = hourly ventilation flow / room volume; room volume = length × width × height.
The result expresses how many room volumes of supplied or exhausted air pass through per hour under the entered steady-flow assumption.
This result follows the calculator's declared inputs, precision, validation boundaries, and model limits.
Input contract
- Room length — m; minimum 1.0E-6; maximum 1000000
- Room width — m; minimum 1.0E-6; maximum 1000000
- Room height — m; minimum 1.0E-6; maximum 1000000
- Average ventilation flow — m³/h; minimum 0; maximum 1000000000
Worked example
| Input | Value |
|---|---|
| Room length | 5 |
| Room width | 4 |
| Room height | 2.5 |
| Average ventilation flow | 300 |
Room volume = 50 m³; ACH = 6.
Assumptions and limits
- Dimensions are in metres and flow is in cubic metres per hour.
- The flow is treated as a room-average exchange rate.
- Mixing effectiveness, filtration, outdoor-air fraction, occupancy, contaminants, and code requirements are not modeled.
Calculator note
Source and methodology
Use the official WorldCalculate methodology policy for the source, formula, precision, and boundary standards behind this calculator.
Planning estimate, not financial, medical, legal, or professional advice. © WorldCalculate — reuse with attribution. Built and curated by Hassan ALRowaie.
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