Where they actually differ
The most decisive specs, ranked by how much they matter — before the full spec table.
| Spec | Coway - Airmega 400 | Winix - C909 |
|---|---|---|
| CADR | 705 m³/h | 500 m³/h |
| Coverage | 60 m² | 50 m² |
| Min noise | 22 dB | 27 dB |
Between the Airmega 400 and C909, the Airmega 400 comes out ahead in cadr / coverage, while the C909 wins on several specs. Overall, the Airmega 400 scores 85.4 and the C909 scores 77.7 on our Mars Score.
Which should you buy?
The Airmega 400 edges ahead on the Mars Score (85.4 vs 77.7), but the 7.7-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 / coverage. The biggest gaps in its favor are cadr, coverage, min noise. The single most decisive one: CADR — 41.00% more. 705 m³/h vs 500 m³/h.
The C909 similarly does not carry a headline advantage on the popular specs — look at the full table for category-specific deltas.
Both ship with comparable true hepa h13+, activated carbon, so those specs do not separate the two — focus on the differences below.
Bottom line: the Airmega 400 is the safer default. The other model is the right choice only when its specific advantages line up with your priorities.
Which should you buy: Coway - Airmega 400 or Winix - C909?
Coway - Airmega 400 leads the current Mars Score by 7.7 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, coverage m2, noise db min.
Choose Winix - C909 if…
Winix - C909 does not lead a decisive measured field here, so choose it for price, ecosystem, design, or availability when those matter more to you.
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 — 41.00% more. 705 m³/h vs 500 m³/h.
- ▲Coverage — 20.00% more. 60 m² vs 50 m².
- ▲Min noise — 5.00 dB less. 22 vs 27.
Why Winix - C909 wins
- No decisive advantages.
Spec comparison
Performance
| Spec | Coway - Airmega 400 | Winix - C909 |
|---|---|---|
| CADR | 705 m³/hlead | 500 m³/h |
| Coverage | 60 m²lead | 50 m² |
| True HEPA H13+ | true | true |
| Activated carbon | true | true |
Smart & Noise
| Spec | Coway - Airmega 400 | Winix - C909 |
|---|---|---|
| Min noise | 22 dBlead | 27 dB |
| Air quality sensor | true | true |
| Smart app | true | true |