
Coway Airmega 400S
Score: 92/100
Blueair Pure 211i Max
Score: 91/100Rankings

The Coway Airmega 400S is a powerful, Wi-Fi-enabled smart air purifier for large spaces up to 3,120 square feet, featuring True HEPA filtration and app control. Its main trade-off is the high cost of annual filter replacements and its bulky size. It is ideal for users managing large open spaces who require powerful purification and remote monitoring capabilities.

The Blueair Blue Pure 211i Max is a high-performance air purifier for large rooms, utilizing HEPASilent™ technology to deliver exceptional CADR ratings and rapid pollutant removal. Its smart app integration and real-time air quality sensors make it a top choice for automated air management, though its bulkier size and single-filter design are notable trade-offs. It is ideal for allergy sufferers and pet owners in large living areas who prioritize cleaning power and efficiency.
| Attribute | ![]() | ![]() |
|---|---|---|
1,560 sq_ftbest | 674 sq_ft | |
400 cfm | 452 cfmbest | |
| ↓ lower better | 22 dBbest | 23 dB |
12 monthsbest | 7.5 months | |
| ↓ lower better | 66 watts | 46 wattsbest |
5 | 6best | |
| ↓ lower better | 24.7 lbs | 22.7 lbsbest |
Click an attribute name to sort · Green = best, red = worst (relative to this comparison)
| Attribute | ![]() | ![]() |
|---|---|---|
Performance(3) | ||
Coverage Area (sq_ft) | 1560 sq_ft | 674 sq_ft |
Clean Air Delivery Rate (CADR) (cfm) | 400 cfm | 452 cfm |
Noise Level (dB) | 22 dB | 23 dB |
Filtration(2) | ||
Filtration Type | True HEPA | HEPA |
Filter Lifespan (months) | 12 months | 7.5 months |
General(1) | ||
Warranty | 5 years | 2 years |
Power & Energy(1) | ||
Power Consumption (watts) | 66 watts | 46 watts |
Design(1) | ||
Weight (lbs) | 24.7 lbs | 22.7 lbs |
Controls(2) | ||
Fan Speeds | 5 | 6 |
Control Interface | Touch/App | App/Touch |

Products in the top-left offer the best value (high score, low price).

Professional reviewers consistently rank it as a class leader in air cleaning performance, awarding it top marks for CADR ratings and large-space coverage up to 3,120 square feet.
Consumers express strong satisfaction with rapid dust removal and smart integration, but complain about the financial impact of yearly filter replacements and occasional wireless pairing difficulties.



Experts praise its superior performance, highlighting the advanced 360-degree intake design that ensures even airflow and efficient cleaning while automatically adjusting to detected pollutants. Reviewers specifically note that the HEPASilent™ technology operates faster and quieter than traditional HEPA systems.
Everyday users consistently praise the purifier for its rapid pollutant reduction capabilities, seamless app integration for monitoring and scheduling, and exceptionally quiet night mode operation. Recurring complaints focus on the single-filter replacement requirement and the unit's bulkier size.