Coway - Airmega 400 vs Dyson - Purifier Big+Quiet Formaldehyde
Between the Airmega 400 and Purifier Big+Quiet Formaldehyde, the Airmega 400 comes out ahead in cadr and min noise, while the Purifier Big+Quiet Formaldehyde wins on coverage. Overall, the Airmega 400 scores 78.3 and the Purifier Big+Quiet Formaldehyde scores 89.1 on our Mars Score.
Which should you buy?
The Purifier Big+Quiet Formaldehyde is the clear pick on raw spec strength, leading by 10.8 points on the Mars Score. The margin is wide enough that the underdog only makes sense if its individual strengths line up with what you specifically need.
Pick the Airmega 400 if you care most about cadr and min noise. The biggest gaps in its favor are cadr, min noise.
Pick the Purifier Big+Quiet Formaldehyde if you care most about coverage. Its strongest claims are coverage.
Both ship with comparable true hepa h13+, activated carbon, so those specs don't separate the two — focus on the differences below.
Bottom line: the Purifier Big+Quiet Formaldehyde is the safer default. The other model is the right choice only when its specific advantages line up with your priorities.
Why Coway - Airmega 400 wins
- ▲CADR — 10.16% more. 705 m³/h vs 640 m³/h.
- ▲Min noise — 2.00 dB less. 22 vs 24.
Why Dyson - Purifier Big+Quiet Formaldehyde wins
- ▲Coverage — 66.67% more. 100 m² vs 60 m².
Spec comparison
Performance
| Spec | Coway - Airmega 400 | Dyson - Purifier Big+Quiet Formaldehyde |
|---|---|---|
| CADR | 705 m³/hlead | 640 m³/h |
| Coverage | 60 m² | 100 m²lead |
| True HEPA H13+ | true | true |
| Activated carbon | true | true |
Smart & Noise
| Spec | Coway - Airmega 400 | Dyson - Purifier Big+Quiet Formaldehyde |
|---|---|---|
| Min noise | 22 dBlead | 24 dB |
| Air quality sensor | true | true |
| Smart app | true | true |
Frequently asked
Spec-level deep dives
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