Compare air purifier CADR with your room
Use connected room volume and a stated air-change basis to compare particle clean-air delivery. Check usable fan speed before making a shortlist.
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Use the whole connected space.
Keep the capacity claims on the same basis.
Required CADR = floor area × ceiling height × comparison ACH ÷ 60. At 300 sq ft, an 8 ft ceiling and 4.8 changes/hour, the arithmetic gives 192 CFM. A 233 CFM candidate gives 233 × 60 ÷ 2,400 ≈ 5.83 equivalent changes/hour.
At 500 sq ft with the same ceiling, that candidate gives about 3.50 changes/hour. The product did not change; the room volume did. Include open connected space rather than measuring only the corner where the unit stands.
Maximum CADR and quiet operation are different inputs.
- Fan speed
A maximum CADR does not establish delivery in Sleep Mode. Get speed-specific data when nighttime noise determines the setting you will use.
- Particles
Smoke, dust and pollen ratings are different measurements. Keep the stated pollutant category with the number.
- Other problems
Particle CADR does not measure gas removal, moisture control or ventilation. Address the actual source and task.
- Room use
Placement, obstructions, operating time and filter condition affect practical performance. These calculations are not a room test.