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HVAC Airflow CFM Calculator

Required CFM from room volume and air-change target.

Compute the required HVAC airflow in cubic feet per minute (CFM) for a room from its volume and the target air changes per hour (ACH). CFM = (room volume · ACH) / 60.

Marcus Laurent By Marcus Laurent
Published Last reviewed 1 min read

Inputs

ft
ft
ft

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

CFM = (length · width · ceiling · ACH) / 60

In depth

Compute the required HVAC airflow in cubic feet per minute (CFM) for a room from its volume and the target air changes per hour (ACH). CFM = (room volume · ACH) / 60.