Airflow CFM Calculator
CFM from Room Size
Calculate required CFM based on room volume and air changes
CFM from Duct Velocity
Calculate CFM from duct size and velocity
Formula
CFM = (Volume x ACH) / 60 | CFM = Duct Area (ft2) x Velocity (FPM)
Frequently Asked Questions
What is CFM?
CFM stands for Cubic Feet per Minute, the standard measure of airflow in HVAC systems. It tells you how much air volume moves through the system each minute.
How many CFM per room?
A general rule is 1 CFM per square foot of floor area. Kitchens and bathrooms need more. The exact amount depends on air changes per hour required.
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