Calculator

Room-volume and CADR calculator

Enter the room’s length, width and ceiling height in feet and choose an air-change scenario. The result is the airflow, in cubic feet per minute (cfm), that the room volume implies at that scenario.

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Inputs and allowed ranges

Room length: 1–200 ft
Room width: 1–200 ft
Ceiling height: 1–30 ft
Air changes per hour (a modeling assumption): 1–12 ACH (default 4)

How to calculate it yourself

Room volume (ft³) = length × width × height.
Modeled CADR (cfm) = volume × air changes per hour ÷ 60, rounded up to a whole cfm.

Worked example

12 × 15 × 8 ft = 1,440 ft³.
At 4 air changes per hour: 1,440 × 4 ÷ 60 = 96 cfm.
At 5 air changes per hour: 120 cfm.

Result

Your result appears here, with the arithmetic shown step by step.

Formula

Room volume (ft³) = length × width × height.
Modeled CADR (cfm) = volume × air changes per hour ÷ 60, rounded up to a whole cfm.

12 × 15 × 8 ft = 1,440 ft³. At 4 air changes per hour: 1,440 × 4 ÷ 60 = 96 cfm. At 5 air changes per hour: 120 cfm.

Healthy Home Audit · Calculator

Room volume and modeled CADR

Date

No result yet. Fill in the inputs, calculate it by hand with the formula below, or use the calculator on healthyhomeaudit.com.

Room volume (ft³) = length × width × height.
Modeled CADR (cfm) = volume × air changes per hour ÷ 60, rounded up to a whole cfm.

Assumptions

Imperial units only.
Room leakage, mixing and real fan settings are not modeled.
The air-change rate is a scenario you choose, not a health threshold.

This calculator organizes arithmetic you can check. It does not test equipment, measure your air or water, or predict a health outcome.

healthyhomeaudit.com

What the result means

At your selected air-change scenario, the result is the airflow this room volume corresponds to. Compare the device’s particle CADR, supported room guidance and actual operating setting. This estimate does not establish a health-protection level.

Room leakage, mixing and real fan settings are not modeled. The default of 4 air changes per hour is a modeling assumption, not a health threshold. EPA explains relevant air-cleaner considerations, and its cleaner-air room page gives smoke-event context; a geometric estimate is not a protective guarantee.

Sources and review

Sources show the date they were accessed. A person has not yet recorded a check date for this page.

EPA: air cleaners in the home, US Environmental Protection Agency (accessed October 13, 2026) — Particle clean-air delivery rate and room fit; EPA does not endorse brands.
EPA: cleaner-air room, US Environmental Protection Agency (accessed October 13, 2026) — Official smoke-event context; website calculation is a geometric estimate, not a protective guarantee.

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