How to calculate CADR and choose by size (quick guide)
The EPA recommends choosing a purifier with sufficient CADR for the room and explains that a higher CADR means more particle filtration over a larger area.
AHAM describes CADR as a measure of the effectiveness/volume of clean air delivered (dust, pollen, smoke).
Step by step
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Volume (m³) = area (m²) × height (m)
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Define the target: 4–5 ACH (domestic use)
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CADR/flow rate (m³/h) ≈ volume × 4 or × 5
Example: room 20 m² × 2.5 m = 50 m³
50 × 5 = 250 m³/h
Important tip
If you leave your windows open for too long, the effectiveness may decrease (more air/pollution enters from outside).