Coway Airmega 350
#11 in Large roomsFull review
For big rooms where you want high certified airflow and low running costs without app features.
Amazon $339$339
The Coway Airmega 350 is the better air purifier overall, rated 3.4 to 2.7. The Coway Airmega 350 leads on value, filter cost and efficiency. The Coway Airmega 350 costs $340 less ($339 vs $679).
AirDoctor AD4000
#15 in Large roomsFull review
A large-room purifier with strong certified CADR and odor filtration, but high filter costs.
Amazon $679$679
Prices were last checked October 22, 2026 and are subject to change; the price and availability shown by the retailer at the time of purchase apply.
Which should you buy?
- Choose the Coway Airmega 350 for value ($0.94 per cfm of smoke CADR vs $1.84 per cfm of smoke CADR), filter cost ($79 a year in filters vs $239.90 a year in filters) and efficiency (6.3 cfm per watt vs 5.6 cfm per watt).
Scores side by side
Each factor is scored 0-100 against the same fixed reference points for every large rooms air purifier; a clear win is highlighted. How we rank explains each one.
| Factor weight | Coway Airmega 350 | AirDoctor AD4000 |
|---|---|---|
| Overall rating | 3.4/5 | 2.7/5 |
| Value 25% | 57 $0.94 per cfm of smoke CADR | 0 $1.84 per cfm of smoke CADR |
| Filter cost 20% | 83 $79 a year in filters | 22 $239.90 a year in filters |
| Quiet 20% | 35 54.7 dB at top speed (maker rating) | 50 noise at top speed not published (neutral score used) |
| Efficiency 15% | 54 6.3 cfm per watt | 45 5.6 cfm per watt |
| Auto mode 10% | 70 PM laser sensor, auto mode | 70 PM2.5 sensor, auto mode |
| Warranty 10% | 0 1-year warranty | 50 warranty not published (neutral score used) |
Specifications
| Coway Airmega 350 | AirDoctor AD4000 | |
|---|---|---|
| Performance | ||
| Smoke CADR | 360 cfm | 370 cfm |
| Dust CADR | 378 cfm | 393 cfm |
| Pollen CADR | 450 cfm | 450 cfm |
| PM2.5 CADR | 369 cfm | 381 cfm |
| CADR certified by | ENERGY STAR | ENERGY STAR |
| Room size (AHAM) | 558 sq ft | 574 sq ft |
| Coverage (maker) | 2,640 sq ft | 2,776 sq ft |
| Noise | 21.5 to 54.7 dB | - |
| Efficiency | ||
| Efficiency (IEF) | 6.3 cfm/W | 5.6 cfm/W |
| ENERGY STAR | Yes | Yes |
| Energy use | 344 kWh/year | 396.2 kWh/year |
| Power at top speed | 62 W | - |
| Filters | ||
| Filter | HEPA | UltraHEPA with carbon/VOC filter and pre-filter (single filter unit) |
| Activated carbon | Yes | Yes |
| Replacement | Airmega 350 Fresh Starter Plus filter | AD4000 filter unit |
| Replacement cost | $79 every 12 months | $119.95 every 6 months |
| Yearly filter cost | $79/year | $239.90/year |
| Ionizer | No | - |
| CARB certified (ozone) | Yes | Yes |
| Controls and build | ||
| Air-quality sensor | PM laser | PM2.5 |
| Auto mode | Yes | Yes |
| Wi-Fi app | No | - |
| Fan speeds | 3 | 6 |
| Dimensions | 23.2 x 12.0 x 12.0 in | - |
| Weight | 17.2 lb | 15.8 lb |
| Warranty | 1 years | - |