Bathroom Ventilation Calculator

This calculator converts room volume and your chosen target air-change rate into cubic feet per minute (CFM).

Length (ft)

Width (ft)

Ceiling height (ft)

Target air changes per hour

Enter dimensions and your target air-change rate.

The formula

CFM = room volume × air changes per hour ÷ 60.

This calculator only performs airflow math. It does not determine the fan required by your local building code, duct layout, static pressure or product instructions.