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Free tools › Contractors › Room airflow (CFM) calculator

Free calculator · no sign-up

Room airflow (CFM) calculator

How much air a room needs: room volume × air changes per hour ÷ 60.

✓ Free✓ Works on your phone✓ Any tax rate

The room

Airflow needed
Room volume
Air changes per hour
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How it’s calculated

CFM = length × width × height × air changes per hour ÷ 60. This is the airflow side only — size heating and cooling equipment with a proper load calculation (in Canada, CSA F280).

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Questions

Is this the same as sizing a furnace or AC?

No. Equipment size comes from a heat-loss/heat-gain calculation. This gives the airflow for a target air-change rate.