Free Air Flow Rate Calculator
Calculate the required CFM (cubic feet per minute) airflow for heating or cooling a room based on its volume and air changes per hour.
ft
ft
ft
ACH
Required Airflow
240 CFM
Room Volume2,400 cu ft
Required Airflow vs Room Length
Air Flow Rate (CFM)
CFM = Room Volume x ACH / 60
ACH (Air Changes per Hour) is how many times the entire room volume is replaced with fresh or conditioned air in one hour. Divide by 60 to convert from cubic feet per hour to cubic feet per minute.
Example Calculation
20 x 15 ft room with 8-ft ceilings at 6 ACH.
- 01Volume = 20 x 15 x 8 = 2,400 cu ft
- 02CFM = 2,400 x 6 / 60 = 240 CFM
Frequently Asked Questions
Learn More
How to Calculate Concrete Needed for Any Project
Learn how to calculate the exact amount of concrete needed for slabs, footings, columns, and other projects. Covers volume formulas, waste factors, and ordering tips.