ACH Calculator
Calculate air changes per hour from airflow in CFM and room dimensions. A fast ACH check for verifying ventilation in residential and commercial spaces.
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Frequently asked questions
What is ACH in HVAC?
ACH means Air Changes Per Hour. It describes how many times the air in a space is replaced in one hour.
How do you calculate ACH?
ACH is calculated as (CFM × 60) divided by room volume in cubic feet.
Why is ACH useful?
ACH helps estimate ventilation rate, air turnover, and how quickly conditioned or ventilated air is replacing room air.
Can ACH replace full ventilation design?
No. ACH is a useful quick metric, but final ventilation design should still follow applicable codes, project requirements, and measured system performance.
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