CADR against room size, not the marketing number

The best air purifiers for 2026

An air purifier is bought on a room-size figure and lived with on CADR — clean air delivery rate — which is the number that actually predicts how fast a room clears, and which manufacturers publish far less prominently than the room size itself. A unit rated for a room twice the size of the one it will sit in, run on a low speed to stay quiet, delivers a fraction of its printed CADR. We compare CADR against the maker's own room-size claim, the filter stages (a true HEPA stage is not the same as an "H13-style" ionic claim), stated filter lifespan and replacement cost, noise at each fan speed rather than just the lowest one, and whether auto mode responds to a built-in sensor or only to a schedule.

By Jean-Benoit Buisson

The models we recommend

1. 

   Xiaomi Smart Air Purifier 4 Compact

   230 m (755 ft)³/h CADR · True HEPA · up to 27 m (89 ft)²

   A compact HEPA purifier Xiaomi rates at 230 m (755 ft)³/h particulate CADR and 185 m (607 ft)³/h formaldehyde CADR for rooms up to 27 m (89 ft)². An OLED touchscreen shows live air quality, sleep mode is rated at 18.3 dB, and the app tracks a 6-12 month filter life.

   Best for: A bedroom or small home office where a compact footprint and a low purchase price matter more than covering a large open-plan room.

   7.0/10

   ≈ $120

   Search Amazon for this model Read the review
2. 

   Philips 900 Series air purifier

   250 m (820 ft)³/h CADR · 3-layer HEPA · 65 m (213 ft)² · 20.5 dB

   Philips rates the 900 Series at a 250 m (820 ft)³/h CADR for rooms up to 65 m (213 ft)², with a 3-layer HEPA filter the brand states removes 99.97% of particles down to 0.003 micron and carries ECARF certification. Sleep mode is published at 20.5 dB and the filter is rated for up to a year.

   Best for: A larger living room or open-plan space where the 65 m (213 ft)² manufacturer rating and long filter life offset the higher entry price.

   8.2/10

   Check price on Amazon Read the review
3. 

   Levoit Core 300S

   195 m (640 ft)³/h CADR · laser sensor · 22 dB sleep mode

   Levoit rates the Core 300S at 195 m (640 ft)³/h CADR with a laser particle sensor that drives an automatic mode and a four-color air-quality ring. Sleep mode is published at 22 dB, and the filter accepts three optional specialty cartridges for pet odor, mold spores or vehicle exhaust.

   Best for: A living room or bedroom where automatic speed adjustment and a quiet sleep mode matter, and where the household wants the option to swap in a specialty filter later.

   7.6/10

   Check price on Amazon Read the review
4. 

   Dyson Purifier Cool PC1

   Sealed HEPA H13 · bladeless tower · fan + purifier

   Dyson's Purifier Cool PC1 combines a bladeless tower fan with a fully sealed HEPA H13 filtration system the brand rates at 99.95% removal down to 0.1 micron, tested to EN 1822. Dyson does not publish a CADR figure or an absolute noise-level rating for this model.

   Best for: A household that wants one device to handle both summer cooling and air purification and is willing to pay a premium for Dyson's sealed-filtration design and app ecosystem.

   8.4/10

   Search Amazon for this model Read the review