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Room Air Changes (ACH) Calculator

Required CFM from room volume and target air changes per hour.

Compute the required ventilation airflow (CFM) for a room from the room volume and a target air-changes-per-hour (ACH) figure (e.g. 4 ACH for kitchens, 8 for bathrooms).

Nadia Almasri By Nadia Almasri
Published Last reviewed 1 min read

Inputs

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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 · height) · ACH / 60.

In depth

Compute the required ventilation airflow (CFM) for a room from the room volume and a target air-changes-per-hour (ACH) figure (e.g. 4 ACH for kitchens, 8 for bathrooms).