HVAC · Air exchange arithmetic
Convert room volume, ACH, and CFM.
Calculate airflow for your entered air-change target and reverse-check measured or available airflow against the same rectangular room volume.
← Room length →↕ Room height↕ Room widthEnclosed air volume
← Measured supply airflow →↕ Target air changes per hourSupply · room · return
1 Measure the enclosed room
2 Enter verified airflow criteria
Transparent calculation
CFM = room cubic feet × ACH ÷ 60.
The reverse check multiplies measured CFM by 60 and divides by room volume. Both directions use values you enter.