Coway - Airmega 400 vs Dyson - Purifier Big+Quiet Formaldehyde
Where they actually differ
The most decisive specs, ranked by how much they matter — before the full spec table.
| Spec | Coway - Airmega 400 | Dyson - Purifier Big+Quiet Formaldehyde |
|---|---|---|
| Coverage | 60 m² | 100 m² |
| CADR | 705 m³/h | 640 m³/h |
| Min noise | 22 dB | 24 dB |
Between the Airmega 400 and Purifier Big+Quiet Formaldehyde, the Airmega 400 comes out ahead in cadr / min noise, while the Purifier Big+Quiet Formaldehyde wins on coverage. Overall, the Airmega 400 scores 85.4 and the Purifier Big+Quiet Formaldehyde scores 89.3 on our Mars Score.
Which should you buy?
The Purifier Big+Quiet Formaldehyde edges ahead on the Mars Score (85.4 vs 89.3), but the 3.9-point gap is small enough that the right pick comes down to which spec advantages matter to you.
Pick the Airmega 400 if you care most about cadr / min noise. The biggest gaps in its favor are cadr, min noise. The single most decisive one: CADR — 10.16% more. 705 m³/h vs 640 m³/h.
Pick the Purifier Big+Quiet Formaldehyde if you care most about coverage. Its strongest claims are coverage. The single most decisive one: Coverage — 66.67% more. 100 m² vs 60 m².
Both ship with comparable true hepa h13+, activated carbon, so those specs do not separate the two — focus on the differences below.
Bottom line: there is no wrong answer here — match the spec advantages to how you actually use the product. The Mars Score parity says both are well-rounded; the differences are about trade-offs, not quality.
Which should you buy: Coway - Airmega 400 or Dyson - Purifier Big+Quiet Formaldehyde?
Dyson - Purifier Big+Quiet Formaldehyde leads the current Mars Score by 3.9 points.The more useful decision is the trade-off behind that result: compare cadr, coverage, min noise against the way you will actually use the product.
Choose Coway - Airmega 400 if…
Coway - Airmega 400 has the measurable edge on cadr m3h, noise db min.
Choose Dyson - Purifier Big+Quiet Formaldehyde if…
Dyson - Purifier Big+Quiet Formaldehyde has the measurable edge on coverage m2.
This is a structured comparison of the published catalog values. It is not a claim of identical real-world performance across every workload; use the linked spec drill-downs and methodology page to inspect the inputs.
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 |