What it calculates
Estimate airflow from room volume and air changes per hour.
Room CFM Calculator
Estimate airflow from room volume and target air changes per hour.
Planning and estimating aid only. Verify project requirements, manufacturer instructions, adopted codes, permits, and field conditions before performing regulated work.
HVAC planning
How to Use This Calculator
Use the field units shown below, then compare your result with the worked example. Choose an ACH basis appropriate to the actual task rather than treating the sample rate as a required standard.
How the calculation works
Room volume = length × width × height. CFM = room volume × air changes per hour ÷ 60.
What the result means
The result is the airflow needed to achieve the entered air-change target.
Convert room volume and air changes into airflow
A 12 × 10 × 8-foot room has 960 cubic feet of volume. At an entered 6 air changes per hour, airflow is 960 × 6 ÷ 60 = 96 cubic feet per minute.
Contractor tip: Choose an ACH basis appropriate to the actual task rather than treating the sample rate as a required standard. Air distribution, outdoor air and room pressure require separate consideration.
Verify the final quantity
ACH is the number of theoretical room-volume changes per hour. It is not automatically an outdoor-air requirement or a measure of contaminant removal in every part of a room.
Good practice: Compare the calculated quantity with plans, specifications, product packaging and current field conditions before purchasing material.