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CFM Calculator

Estimate CFM airflow for exhaust fans and ventilation.

Airflow in CFM equals room volume × air changes per hour ÷ 60. A 12 × 15 ft room with an 8 ft ceiling is 1,440 cu ft; at 6 ACH that's 144 CFM. HVAC supply sizing uses roughly 400 CFM per ton of cooling, or about 1 CFM per square foot. Enter your room size and target air changes for required CFM.

How does the cfm calculator work?

CFM = (room volume in ft³ × ACH) ÷ 60. Common ACH targets: bathrooms 8, kitchens 15, workshops 6, bedrooms 4.

What else do people ask about this calculator?

What CFM do I need for a bathroom?

Code minimum is 50 CFM, but sizing by 8 ACH keeps a large bathroom clear. A 10×8×8 ft bath needs ~85 CFM.

How is CFM calculated?

Multiply room volume by desired air changes per hour and divide by 60 minutes to get cubic feet per minute.

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