Coway Airmega 400 vs Blueair Blue Pure 211i Max
The two large-room flagships buyers cross-shop. One wins on output, coverage and efficiency at once. The other wins the only safety number either register publishes.
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The Blueair 211i Max wins output, coverage and efficiency simultaneously: 435 CFM across 674 certified square feet at 9.0 CFM per watt, on less electricity than the Coway. The Coway Airmega 400 wins the ozone question: 0.00 ppb measured and no ion stage against 2 ppb and a disputed one.
These two land on the same shortlist whenever somebody is buying for a large open-plan space, and unusually for this category the comparison is not close on either axis. It is just that they are different axes.
The numbers, side by side
| Coway Airmega 400 | Blueair 211i Max | |
|---|---|---|
| Smoke CADR | 376 CFM | 435 CFM |
| Dust CADR | 384 CFM | 453 CFM |
| Pollen CADR | 409 CFM | 450 CFM |
| PM2.5 CADR | 380 CFM | 444 CFM |
| Certified room size | 583 sq ft | 674 sq ft |
| Annual energy (certified) | 366 kWh | 256 kWh |
| Electricity per year | $67 | $47 |
| Air per watt | 6.1 CFM/W | 9.0 CFM/W |
| Measured ozone | 0.00 ppb | 2 ppb |
| Ionizer | None | Registers disagree |
| Filter classification | Composite Filter | HEPA-Type |
| Registers listed in | ENERGY STAR | AHAM and ENERGY STAR |
Electricity costs on this page use 18.34¢ per kWh, the U.S. average residential price for June 2026 from the U.S. Energy Information Administration, Electric Power Monthly, Table 5.3. Your rate is on your bill and is probably not this one; multiply the kWh figure by your own rate and you have your number.
On performance, the Blueair wins three ways at once
435 against 376 smoke CADR is 16% more air. 674 against 583 certified square feet is the same 16% expressed as coverage. Neither of those is remarkable on its own.
What is remarkable is that it does this on 256 certified kWh a year against the Coway’s 366 — 30% less electricity for 16% more air. Normally more output costs more power; here it does not, and 9.0 CFM per watt is the highest figure on this site by a clear margin. Over the life of a machine that runs continuously, that gap is real money.
On what the machine adds, the Coway wins
The Airmega 400 is classified fan-and-filter by ENERGY STAR with a measured ozone emission of 0.00 ppb. No ion generator, no plasma stage, nothing to switch off.
The Blueair is the site’s standing example of two registers disagreeing. AHAM classifies the Max range “Fan Filter with Ion Generator”; ENERGY STAR records “Fan and Filter” and measures 2 ppb. Two parts per billion is a small number and far below the 50 ppb program limit. It is not zero, Blueair does not document the stage as defeatable, and EPA’s advice is to avoid portable air cleaners that intentionally produce ozone because ozone is a lung irritant.
Quick picks
Both machines, plus the large-room alternative that takes the ozone question off the table without giving up coverage.
| # | Product | Best for | Certified CADR | Price |
|---|---|---|---|---|
| 1 |  The stronger machine Blueair Blue Pure 211i Max 435 certified CFM across 674 sq ft at 9.0 CFM per watt. | Open-plan spaces above 500 sq ft | 435CFM smoke AHAM VERIFIDE | |
| 2 |  The safer machine Coway Airmega 400 376 certified CFM with 0.00 ppb measured ozone and no ion stage. | Large rooms, verified Coway | 376CFM smoke ENERGY STAR verified | |
| 3 |  Zero ozone with more room LEVOIT Core 600S 391 certified CFM across 606 sq ft, also 0.00 ppb measured. | Large open-plan rooms | 391CFM smoke ENERGY STAR verified |
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The picks
Blueair Blue Pure 211i Max
Blueair · model 3613111100 (Blue Pure 211i Max)
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The most air per watt of anything here and by some distance the largest certified coverage — 674 square feet. It does carry an ion generator, which is the reason it is not our asthma pick.
435 smoke / 453 dust / 450 pollen CFM · 444 PM2.5
- Certified room size
- 674 sq ft
- Energy / year
- 256 kWh
- Electricity / year
- $47
- Air per watt
- 9 CFM/W
- Power draw
- 44 W
- Noise
- Not published
- Measured ozone
- 2 ppb
- Filter class
- HEPA-Type
Ion generator — fitted
The two registers disagree: AHAM classifies this model 'Fan Filter with Ion Generator' while ENERGY STAR records it as 'Fan and Filter'. ENERGY STAR's measured ozone figure is 2 ppb. We report both rather than picking the flattering one.
More certified air, more certified room and better air per watt than anything else we cover, at $47 a year. For a large open-plan space in a household with no asthma, it is genuinely hard to argue against on the numbers.
The honest con: the ion generator AHAM records, the 2 ppb ENERGY STAR measures, the fact that Blueair does not document the stage as switchable, and a HEPA-Type rather than HEPA filter classification.
Coway Airmega 400
Coway · model Airmega 400 (AP-2015F)
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The Coway that is actually in a certification register: 376 certified smoke CADR, 583 square feet, zero measured ozone. If you want a Coway, this is the one with third-party numbers.
376 smoke / 384 dust / 409 pollen CFM · 380 PM2.5
- Certified room size
- 583 sq ft
- Energy / year
- 366 kWh
- Electricity / year
- $67
- Air per watt
- 6.1 CFM/W
- Noise
- Not published
- Measured ozone
- 0 ppb
- Filter class
- Composite Filter
- AHAM rule, 500 sq ft
- Clears it (334 needed)
No ionizer — filtration only
ENERGY STAR classifies this unit 'Fan and Filter', 0.00 ppb measured ozone.
376 certified smoke CADR across 583 certified square feet with 0.00 ppb measured ozone and no ion generator, plus a genuine activated carbon layer that addresses odor rather than particulate. This is the Coway with third-party numbers, which is worth saying because the Coway most people buy is not.
The honest con: $67 a year for less air than the Blueair, no filter classification from the register, and no published filter interval or price in our sources.
LEVOIT Core 600S
LEVOIT · model Core 600S (LAP-C601S-WUS)
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391 certified smoke CADR is real large-room capability, and it is honest about needing 387 kWh a year to deliver it — the highest electricity bill of any unit we recommend.
391 smoke / 398 dust / 436 pollen CFM · 394 PM2.5
- Certified room size
- 606 sq ft
- Advertised coverage
- 2,909 sq ft at 1 air change per hour
- Energy / year
- 387 kWh
- Electricity / year
- $71
- Air per watt
- 6 CFM/W
- Power draw
- 49 W
- Noise
- 26-55 dB
- Measured ozone
- 0 ppb
- Filter class
- HEPA-Type
- AHAM rule, 550 sq ft
- Clears it (367 needed)
No ionizer — filtration only
ENERGY STAR classifies this unit 'Fan and Filter', 0.00 ppb measured ozone.
Buyer-first: if the Coway appeals because of the zero but 583 square feet is not enough, the Core 600S certifies 391 CFM across 606 square feet with the same 0.00 ppb measured ozone and no ion stage.
The honest con: $71 a year at 387 certified kWh is the highest running cost of anything we recommend — worse than either machine above — and its filter is recorded HEPA-Type.
The verdict
Common questions
Which is better, the Airmega 400 or the Blueair 211i Max?
Does the Blueair 211i Max have an ionizer?
Which covers a bigger room?
Which is cheaper to run?
Sources
- AHAM VERIFIDE directory of certified room air cleaners
- ENERGY STAR certified room air cleaners database
- EPA — Guide to Air Cleaners in the Home
Figures were read on the dates shown against each source. If one has changed, or if we have got something wrong, tell us and we will correct the page.
Read next
- Room sizeThe Best Air Purifiers for Large RoomsCertified for 500+ square feet, ranked on real coverage and what each costs to run.
- CADR & costBlueair vs LEVOITBlueair wins air-per-watt by a distance. Every Blueair here also has an ion stage and a measured ozone figure; every LEVOIT reads 0.00.
- Pet allergiesCoway Airmega 400 vs Airmega Mighty AP-1512HH376 certified CFM and 0.00 ppb ozone against 233 claimed CFM and an unmeasured bipolar stage — from the same brand.