Air Flow Rate Calculator Formula
Understand the math behind the air flow rate calculator. Each variable explained with a worked example.
Formulas Used
Required Airflow
cfm = room_volume * ach / 60Room Volume
volume = room_volumeVariables
| Variable | Description | Default |
|---|---|---|
room_length | Room Length(ft) | 20 |
room_width | Room Width(ft) | 15 |
ceiling_height | Ceiling Height(ft) | 8 |
ach | Air Changes per Hour(ACH) | 6 |
room_volume | Derived value= room_length * room_width * ceiling_height | calculated |
How It Works
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.
Worked Example
20 x 15 ft room with 8-ft ceilings at 6 ACH.
room_length = 20room_width = 15ceiling_height = 8ach = 6
- 01Volume = 20 x 15 x 8 = 2,400 cu ft
- 02CFM = 2,400 x 6 / 60 = 240 CFM
Ready to run the numbers?
Open Air Flow Rate Calculator