Air Change Rate

Not Reviewed
Equation / Last modified by KurtHeckman on 2019/02/21 01:57
Anastase.Air Change Rate

The Air Change Rate calculator computes the number of times per hour the air in a space changes based on the flow rate of fresh air (q) and the volume of the space (v).

INSTRUCTIONS: Choose units and enter the following:

  • (q) This is the flow rate of fresh air into the space
  • (v) This is the total volume of the space (e.g. volume of a room)

Air Change Rate (n):  The calculator returns the change rate in changes per hour.  However this can be automatically converted to compatible units via the pull-down menu.

Ventilation Calculators

The Math / Science

The formula for Air change rate (air changes per hour) is:

    n = q / v      


  •     n = air changes
  •     q = fresh air flow through the room (Cubic Feet per Minute,  cfm)
  •     v = volume of the room (Cubic Feet)