CFM Calculator

Use case for a CFM Calculator

The CFM formula or cubic feet per minute formula measures the volume of air flow – typically for fans and ventilation systems – ensures that there is sufficient air circulation to maintain indoor air quality based on the dimensions of a room.

Air Flow Calculator

Rectangle Duct

Circular Duct

Results:

  • LFM: N/A ft/min
  • m/s: N/A
  • MPH: N/A
  • CFM: N/A ft³/min
  • m³/hr: N/A
  • L/s: N/A

Formula for CFM calculations

To calculate CFM (Cubic Feet per Minute), start by determining the volume of the room by multiplying the floor area (length × width) by the ceiling height to get the total volume in cubic feet. Next, consider ACH (Air Changes per Hour) numbers to determine how often the air in a room needs to be replaced with fresh air each hour. To convert ACH to CFM, divide the result by 60 to account for the number of minutes in an hour. The formula for CFM is as follows:

CFM = (Room’s volume in cubic feet × ACH) / 60

Using this formula, you can determine the required airflow rate for the room in cubic feet per minute.