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Head-to-head · Best Air Purifiers

Blueair Blue Pure 311i Max vs Coway Airmega 400S

Which is the better buy? Side-by-side on rating, price, strengths, and watch-outs — with the published ratings we averaged to get there.

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The short answer

Coway Airmega 400S comes out ahead by a clear margin (4.5 vs 4.1). Coway Airmega 400S is best for: Owners of large open-concept living areas. Read the strengths below before deciding.

Blueair Blue Pure 311i Max
Ranked #4 in Best Air Purifiers
Blueair Blue Pure 311i Max
2 sources$169.99as of Oct 16

TechGearLab's best overall air purifier (80/100) and a 3.5/5 'Good' from PCMag: a light, quiet, app- and voice-controlled purifier for medium to large rooms that cleared smoke quickly in both outlets' tests. Its HEPASilent system relies on an always-on ionizer, and PCMag notes limited air quality readings and filter options.

Strengths
  • — Removed over 80% of particles in 10 minutes and had TechGearLab's 200 sq ft lab 99% clean by 27 minutes
  • — Cleared a 110 sq ft office from a PM2.5 reading of 200 to 0 in 14 minutes in PCMag's incense test
  • — Quiet: PCMag measured 52dB on high and 33dB on low
Watch-outs
  • — The HEPASilent system uses an always-on ionizer and is not a True HEPA filter, per TechGearLab
  • — TechGearLab found the child lock is not fully childproof
  • — PCMag notes limited air quality readings (PM2.5 only, no on-device numbers) and no application-specific filter options
$169.99 · Check Price on AmazonFull review →
Coway Airmega 400S
Higher ratedRanked #1 in Best Air Purifiers
Coway Airmega 400S
2 sources$749as of Oct 10

Large spaces are the Coway Airmega 400S's job, and it cleans up to 3,120 sq. ft. quickly while staying quiet in sleep mode. Air cleaning performance is the strength, and the smart controls are genuinely convenient. The drawbacks worth weighing before buying: high operating costs and a large physical footprint.

Strengths
  • — Covers spaces up to 3,120 sq. ft. with high efficiency, per TechGearLab
  • — Removes 100% of particulates in 45 minutes, according to TechGearLab
  • — Operates at whisper-quiet 22 dB in sleep mode, per Breathe Quality
Watch-outs
  • — High operating cost due to expensive replacement filters
  • — Bulky dimensions (14.8" x 22.8" x 14.8") occupy significant floor space, as Breathe Quality notes
  • — Requires a mobile app to access certain smart features
$749 · Buy at cowaymega.comFull review →

How they stack up

Blueair Blue Pure 311i Max

PCMag points out that two 311i Max units cost about the price of one Dyson Purifier Cool TP07, which adds an oscillating fan and more detailed air quality readings. TechGearLab suggests the Levoit Core 400S (the 400S-P version it tested) as the ionizer-free, family-friendly alternative that is nearly as powerful.

Coway Airmega 400S

The Coway Airmega 400S dominates in raw coverage power, cleaning spaces up to 3,120 sq. ft., which far exceeds the 540 sq. ft. limit of the Blueair Blue Pure 211+ and the 99 sq. ft. limit of the Dyson TP07. While it shares smart features with the Levoit Core 400S, the Coway is physically much bulkier and incurs higher long-term filter costs than the Levoit.

Specs side-by-side

SpecBlueair Blue Pure 311i MaxCoway Airmega 400S
Listed CADRPollen 365 cfm, Dust 314 cfm, Smoke 283 cfm (TechGearLab)—
Rated Room SizeUp to 929 sq ft in 30 minutes (PCMag)—
FiltrationHEPASilent: pleated particle filter plus ionizer, carbon layer, washable fabric pre-filter—
Measured Weight7.3 lbs (TechGearLab)—
Dimensions19 x 12.5 x 12.5 in14.8 x 22.8 x 14.8 inches
Smart FeaturesWi-Fi app, Amazon Alexa, Google Assistant—
Replacement Filter$44.99, up to nine months (PCMag)—
Energy StarYes—
CADR—328 cfm
Room Coverage—3,120 sq. ft.
Noise Level—22 dB
Filtration System—HyperCaptive (Pre-filter, Carbon, HEPA)
Weight—24.7 lbs
Power Consumption—66 W
Filter Lifespan—Up to 12 months
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