Air Purifier Calculator: CADR Needed for Your Room Size
Free tool · Updated October 2, 2026 · By CouponTalk
Your result
Enter your measurements to see your result.
Quick answer
An air purifier's CADR (clean air delivery rate) should clean your room's air 4–5 times an hour in polluted Indian cities. CADR needed (m³/h) = room volume in m³ × air changes per hour. A 150 sq ft bedroom with a 10 ft ceiling is about 42 m³, so it needs about 210 m³/h for 5 air changes. Manufacturers' "room size" claims often assume fewer changes.
How to use this calculator
- Enter the room's floor area in sq ft.
- Enter ceiling height.
- Choose your typical pollution level.
Formula
CADR needed (m³/h) = Area (sq ft) × Height (ft) × 0.0283 × Air changes per hour
1 m³/h ≈ 0.59 cfm.
These are typical figures for Indian homes. Check the product spec sheet, and ask an electrician or installer before you buy or fit anything.
Frequently asked questions
What CADR do I need for a 200 sq ft room?
For a 200 sq ft room with a 10 ft ceiling (about 57 m³), aim for 230–340 m³/h CADR, depending on how polluted the air is.
Does a HEPA filter remove PM2.5?
A true HEPA (H13) filter captures at least 99.97% of particles of 0.3 microns, which covers PM2.5. Replace filters as the manufacturer recommends.
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