CFM Calculator: Cubic Feet per Minute Airflow

Your details

Room mode: find CFM from volume and ACH. Velocity mode: area x air speed. Reverse: what ACH does your unit deliver?
Interior length of the room.
ft
Interior width of the room.
ft
Floor-to-ceiling height.
ft
How many times per hour the entire room air volume should be replaced. See the reference table for typical values.
Required airflow
270CFM

Cubic feet per minute of air needed

Room volume2,700ft³
Airflow (m³/h)458.7m³/h
Airflow (L/min)7,646L/min
CFM270
m³/h458.7

You need 270.0 CFM to achieve 6 air changes per hour.

  • That is 459 m³/h or 7646 L/min in metric units.
  • Your room volume is 2700 ft³; the entire air supply cycles roughly every 10 minutes.

Next stepMatch this CFM to a fan or HVAC unit with at least that rated capacity, then add 10-20% as a buffer for duct losses and filter resistance.

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