Dyson - Purifier Big+Quiet Formaldehyde vs Winix - C909
Between the Purifier Big+Quiet Formaldehyde and C909, the Purifier Big+Quiet Formaldehyde comes out ahead in coverage and cadr, while the C909 wins on several specs. Overall, the Purifier Big+Quiet Formaldehyde scores 89.1 and the C909 scores 66.8 on our Mars Score.
Which should you buy?
The Purifier Big+Quiet Formaldehyde is the clear pick on raw spec strength, leading by 22.3 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 Purifier Big+Quiet Formaldehyde if you care most about coverage and cadr. The biggest gaps in its favor are coverage, cadr, min noise.
The C909 similarly doesn't 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 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 Dyson - Purifier Big+Quiet Formaldehyde wins
- ▲Coverage — 100.00% more. 100 m² vs 50 m².
- ▲CADR — 28.00% more. 640 m³/h vs 500 m³/h.
- ▲Min noise — 3.00 dB less. 24 vs 27.
Why Winix - C909 wins
- No decisive advantages.
Spec comparison
Performance
| Spec | Dyson - Purifier Big+Quiet Formaldehyde | Winix - C909 |
|---|---|---|
| CADR | 640 m³/hlead | 500 m³/h |
| Coverage | 100 m²lead | 50 m² |
| True HEPA H13+ | true | true |
| Activated carbon | true | true |
Smart & Noise
| Spec | Dyson - Purifier Big+Quiet Formaldehyde | Winix - C909 |
|---|---|---|
| Min noise | 24 dBlead | 27 dB |
| Air quality sensor | true | true |
| Smart app | true | true |
Frequently asked
Spec-level deep dives
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