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Free Room CFM Calculator — HVAC Airflow
Calculate the required airflow in cubic feet per minute (CFM) for a room based on its volume and the desired air changes per hour (ACH). This is a key calculation for HVAC system sizing, ventilation design, and indoor air quality planning.
Frequently asked questions
How do I calculate CFM for a room?
CFM = (Room Volume in cubic feet × ACH) ÷ 60. For example, a 1,200 cu ft room with 6 ACH requires (1,200 × 6) ÷ 60 = 120 CFM.
What is a typical ACH for a residential room?
Residential bedrooms typically need 4–6 ACH, living areas 6–8 ACH, kitchens 7–10 ACH, and bathrooms 6–10 ACH. Commercial spaces vary widely by use.
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