Clean air room calculator

Size an air purifier for the room you actually use

Enter room dimensions and a smoke CADR. Get the minimum filtration target, expected air changes, and the number of units needed.

Room and purifier details

Use the purifier’s smoke CADR—not its maximum fan airflow.

Room filtration plan

Room volume

1440 ft³

Minimum smoke CADR

117 CFM

Installed smoke CADR

120 CFM

Estimated air changes/hour

5 ACH

Target status

Meets the EPA sizing target

This room needs about 1 purifier unit(s) at the entered smoke CADR.

Sizing is based on the EPA smoke CADR table and adjusted for ceiling height. The ACH estimate assumes rated airflow is delivered in the room.

EPA’s smoke CADR sizing table is equivalent to about 0.65 CFM per square foot for an 8-foot ceiling.
Higher ceilings scale the minimum CADR in proportion to room volume.
Installed CADR is the purifier’s verified smoke CADR multiplied by the number of units.
Air changes per hour assume the purifier can deliver its rated CADR in the room; placement and filter condition still matter.

Trust Signals

Review policy

July 20, 2026. We update supporting pages when calculator logic, live data behavior, or source framing changes.

Primary sources

AQI uses EPA / AirNow breakpoint logic. Cigarette-equivalent framing follows Berkeley Earth’s PM2.5 interpretation.

Live data layer

City pages use EPA AirNow where supported, with cached fallbacks and planning baselines if the API fails or coverage is unavailable.

Use the smoke CADR from an AHAM-verified or manufacturer specification. Dust and pollen CADR are not interchangeable with smoke CADR.

For a planning estimate, yes: add their smoke CADR when both run in the same room. Real airflow still depends on placement and obstructions.

Not necessarily. CADR measures particle removal. Gases and odors require suitable activated-carbon or other gas-phase media.