Air Changes per Hour Calculator
Determine ventilation effectiveness by calculating how many times the air in a room is replaced each hour.
CalcSimpler Examples
- 200 CFM in 1200 ft³ ⇒ 10 ACH
- 400 CFM in 1600 ft³ ⇒ 15 ACH
FAQ
What is a good ACH?
Living spaces often aim for 4–6 ACH; hospitals require higher rates.
Does ceiling height matter?
Yes, volume includes height to capture total room air.
Can I use metric units?
Yes, convert to cubic feet and CFM before using.
Additional Information
- ACH = (CFM × 60) ÷ room volume.
- Higher ACH improves air quality by removing pollutants.
CalcSimpler