Construction

CFM Calculator

Find cubic feet per minute from room volume and air changes.

Calculated Output

Air flow (CFM) 66.667

Formula: CFM = volume × ACH ÷ 60

Step-by-Step Breakdown

1. Values used:

2. Room volume = 1,000

3. Air changes per hour = 4 ACH

5. Air flow = 66.667CFM

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The math behind it

CFM = room volume (ft³) × target ACH ÷ 60.

1,000 ft³ at 4 ACH → 66.7 CFM.

ACH?

Air changes per hour — how many times the room's air is replaced per hour.