basic

Duct CFM Sizing from Room Area Calculator

CFM ≈ (room_sqft · ceiling_height) · ACH / 60.

Compute the recommended supply-duct airflow (CFM) for a room from its square footage, ceiling height, and target air-changes-per-hour (ACH). General guidance: 4 ACH for bedrooms, 6 for living rooms, 8 for kitchens, 12 for bathrooms. CFM = (sqft · height · ACH) / 60.

Marcus Laurent By Marcus Laurent
Published Last reviewed 1 min read

Inputs

ft²
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 = (sqft · height · ACH) / 60.

In depth

Compute the recommended supply-duct airflow (CFM) for a room from its square footage, ceiling height, and target air-changes-per-hour (ACH). General guidance: 4 ACH for bedrooms, 6 for living rooms, 8 for kitchens, 12 for bathrooms. CFM = (sqft · height · ACH) / 60.