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Room Airflow Change Rate Calculator

Compare airflow volume per hour with the volume of a room.

  • Formula & worked example
  • Private in your browser
  • No signup
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Calculator inputs

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How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Edit a calculated value to solve backwards, or lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

Private by default

Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.

Formula and method

Divide hourly airflow by room volume. A room with 20 square meters of floor area and a 3-meter height has a volume of 60 cubic meters. Airflow of 3 cubic meters per minute gives three air changes per hour.

Air changes per hour = airflow per minute × 60 ÷ (floor area × height)

Worked example

Enter these known values and leave the other values blank.

Area
20 m²
Height
3 m
Airflow
3 m³ / min
Air changes per hour
3 ACH

Assumptions and limitations

  • It is a nominal airflow-to-volume ratio. Air mixing, outdoor-air fraction, filtration and contaminant sources affect actual performance. It does not establish infection risk or compliance with a ventilation requirement.
  • Use the units shown beside each field. This model assumes the stated relationship and does not account for quantities left out of the formula.

Common questions

Does this measure how safe the air is?

It is a nominal airflow-to-volume ratio. Air mixing, outdoor-air fraction, filtration and contaminant sources affect actual performance. It does not establish infection risk or compliance with a ventilation requirement.

References

The calculation equations, inverse formulas, units, and input rules were imported from this source. Bookify provides the interface and equation solver.

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