Buying guide · Air purifiers
The best air purifiers for large rooms and open-plan spaces
Our top picks: the Blueair Blue Pure 211i Max, the Levoit Core 600S and the Coway Airmega 400. Big rooms are where purifier marketing stretches furthest: '3,000 ft²' usually means cleaning the air once an hour. For a room that feels clean, AHAM's standard is about five clean-outs an hour, and only a few purifiers manage that above 40 m².
These are the ones that do, ranked by their verified smoke CADR.
Updated · 4 picks · figures from AHAM, Energy Star, NIOSH and the makers · no brand pays to be listed
| Purifier | Smoke CADR | Everyday room | Smoky days | Quietest | Filter | Price |
|---|---|---|---|---|---|---|
| Blueair Blue Pure 211i Max | 435 cfm | 63 m² (674 ft²) | 40 m² | 23 dB | — | $349.99at blueair.com |
| Levoit Core 600S | 391 cfm | 56 m² (606 ft²) | 36 m² | 26 dB | $59.99every 6–12 months | $299.99at levoit.com |
| Coway Airmega 400 | 376 cfm | 54 m² (583 ft²) | 35 m² | 22 dB | $129.00up to 1 year | $649.00at cowaymega.com |
| Honeywell HPA300 | 300 cfm | 43 m² (465 ft²) | 28 m² | — | $89.95 | $269.95at honeywellstore.com |
Everyday room: AHAM's room size for the smoke CADR (about five clean-outs an hour). Smoky days: AHAM's stricter advice for smoke, a CADR at least equal to the floor area in square feet. Quietest: the maker's figure for its lowest setting. Filter: the replacement's list price at its maker.
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Most clean air
Blueair Blue Pure 211i Max
The most clean air here, about 63 m² by AHAM's room size, and it draws air from all sides.
- Cleans
- 63 m² day to day, 40 m² on smoky days
- Quietest
- 23 dB
$349.99at blueair.com
Large rooms
Levoit Core 600S
About 56 m² with a laser sensor and app, at a lower list price than the Blueair.
- Cleans
- 56 m² day to day, 36 m² on smoky days
- Quietest
- 26 dB
- Filter
- $59.99, every 6–12 months
$299.99at levoit.com
Big rooms
Coway Airmega 400
About 54 m², two filters and a 5-year warranty.
- Cleans
- 54 m² day to day, 35 m² on smoky days
- Quietest
- 22 dB
- Filter
- $129.00, up to 1 year
$649.00at cowaymega.com
No-frills power
Honeywell HPA300
About 43 m² with simple controls; three R filters make a full change.
- Cleans
- 43 m² day to day, 28 m² on smoky days
- Filter
- $89.95
$269.95at honeywellstore.com
What size do you need?
The single biggest mistake is a purifier too small for the room. Type yours in to see the clean air it needs, and which picks get there.
You need a smoke CADR of at least 108 cfm (your room is about 161 ft²).
On this list: Blueair Blue Pure 211i Max, Levoit Core 600S, Coway Airmega 400, Honeywell HPA300.
The rule is AHAM's, the US body that certifies CADR ratings: two-thirds of the floor area in square feet day to day, the full floor area for smoke. It assumes an 8 ft (2.4 m) ceiling; for a higher one, aim a little above it.
How we chose
40 m² and up, verified
Each covers at least about 40 m² by AHAM's room size, worked out from its verified smoke CADR.
One machine, not two
Big enough to replace two small purifiers in an open-plan room.
Filters you can afford to change
Large purifiers eat filters; each pick's replacement is easy to find.
We haven't lab-tested these ourselves. The rankings rest on independent ratings (AHAM's verified CADR, Energy Star's listings, NIOSH approvals) and the makers' own figures, each shown on the product's page with where it's from. No brand pays to be listed, and the order doesn't change with commission. We earn a small commission when you buy through our links.
Questions
- Can one air purifier clean a whole house?
- Not to the standard of a closed room. A purifier rated for '2,000 ft²' usually means one clean-out an hour. For a large open-plan space, pick one sized for it by AHAM's room size, or use two.
- What CADR do I need for a 500 sq ft room?
- For everyday use, a smoke CADR of about 330 cfm (two-thirds of the floor area); for smoke or heavy smog, about 500 cfm.
Before you buy
Check how bad the air gets where you live
A purifier matters most where the air is often unhealthy. See today's reading and the past week for your city, from the nearest ground stations.