Heating, Cooling & Ventilation calculator
Ventilation Rate Calculator
Calculate ventilation airflow in CFM or m³/h from room volume and a target air-change rate.
Calculate ventilation airflow in CFM or m³/h from room volume and a target air-change rate. Keep the dimensions and units consistent, then check the figures that describe the product or layout you will really use. In this calculation, room volume and target ACH can change the answer materially. Ventilation requirements depend on occupancy and room use as well as volume. Check the applicable design guidance before selecting fans or ducts.
What you need to enter
The Ventilation Rate Calculator uses the following project information to calculate the result.
- Room volume
- Air changes per hour
Calculator result
Required airflow (CFM / m³/h)
How the Ventilation Rate Calculator works
To produce required airflow (cfm / m³/h), the Ventilation Rate Calculator applies airflow = room volume × ACH ÷ time conversion. The engine is configured for ventilation airflow for a target air-change rate, not as a generic text estimate. Check room volume and target ACH, since an incorrect value there can materially change the result.
Ventilation Rate Calculator worked example
Ventilation Rate Calculator example: a 45 m³ room targeted at 5 air changes per hour needs 225 m³/h of ventilation airflow. Convert that result to CFM if required, then check whether occupancy or room use calls for a higher design rate. The worked figure becomes more useful when room volume and target ACH is taken from the real product or site rather than a generic default.
Important calculation assumptions
For ventilation airflow for a target air-change rate, ventilation requirements depend on occupancy and room use as well as volume. Check the applicable design guidance before selecting fans or ducts.
Frequently asked questions
What do I need to enter before the Ventilation Rate Calculator can give a useful result?
To estimate ventilation airflow for a target air-change rate, use a measured or calculated room volume and the target air-change rate. Keep airflow units consistent when converting between CFM and m³/h. Use measured or manufacturer-specific values wherever they are available.
Which details about room volume and target ACH should I verify for the Ventilation Rate Calculator?
In the Ventilation Rate Calculator, errors in room volume and target ACH can materially affect the result. Ventilation requirements depend on occupancy and room use as well as volume. Check the applicable design guidance before selecting fans or ducts.
Is the Ventilation Rate Calculator a final sizing calculation?
Once the Ventilation Rate Calculator has produced a result, use the airflow result as a ventilation target, then account for occupancy, duct resistance, fan performance and the ventilation guidance applicable to the room type.