Between the Blue Pure 311i+ Max and C909, the Blue Pure 311i+ Max comes out ahead in min noise, while the C909 wins on coverage. Overall, the Blue Pure 311i+ Max scores 61.3 and the C909 scores 66.8 on our Mars Score.
Which should you buy?
The C909 edges ahead on the Mars Score (61.3 vs 66.8), but the 5.5-point gap is small enough that the right pick comes down to which spec advantages matter to you.
Pick the Blue Pure 311i+ Max if you care most about min noise. The biggest gaps in its favor are min noise.
Pick the C909 if you care most about coverage. Its strongest claims are coverage.
Both ship with comparable cadr, true hepa h13+, activated carbon, so those specs don't separate the two — focus on the differences below.
Bottom line: the C909 is the safer default. The other model is the right choice only when its specific advantages line up with your priorities.
Why Blueair - Blue Pure 311i+ Max wins
- ▲Min noise — 4.00 dB less. 23 vs 27.
Why Winix - C909 wins
- ▲Coverage — 42.86% more. 50 m² vs 35 m².
Spec comparison
Performance
| Spec | Blueair - Blue Pure 311i+ Max | Winix - C909 |
|---|---|---|
| CADR | 500 m³/h | 500 m³/h |
| Coverage | 35 m² | 50 m²lead |
| True HEPA H13+ | true | true |
| Activated carbon | true | true |
Smart & Noise
| Spec | Blueair - Blue Pure 311i+ Max | Winix - C909 |
|---|---|---|
| Min noise | 23 dBlead | 27 dB |
| Air quality sensor | true | true |
| Smart app | true | true |
Frequently asked
Spec-level deep dives
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