Blueair - Blue Pure 311i+ Max 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 | Blueair - Blue Pure 311i+ Max | Dyson - Purifier Big+Quiet Formaldehyde |
|---|---|---|
| Coverage | 35 m² | 100 m² |
| CADR | 500 m³/h | 640 m³/h |
| Min noise | 23 dB | 24 dB |
Between the Blue Pure 311i+ Max and Purifier Big+Quiet Formaldehyde, the Blue Pure 311i+ Max comes out ahead in min noise, while the Purifier Big+Quiet Formaldehyde wins on coverage / cadr. Overall, the Blue Pure 311i+ Max scores 77.4 and the Purifier Big+Quiet Formaldehyde scores 89.3 on our Mars Score.
Which should you buy?
The Purifier Big+Quiet Formaldehyde is the clear pick on raw spec strength, leading by 11.9 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 Blue Pure 311i+ Max if you care most about min noise. The biggest gaps in its favor are min noise. The single most decisive one: Min noise — 1.00 dB less. 23 vs 24.
Pick the Purifier Big+Quiet Formaldehyde if you care most about coverage / cadr. Its strongest claims are coverage, cadr. The single most decisive one: Coverage — 185.71% more. 100 m² vs 35 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: 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.
Which should you buy: Blueair - Blue Pure 311i+ Max or Dyson - Purifier Big+Quiet Formaldehyde?
Dyson - Purifier Big+Quiet Formaldehyde leads the current Mars Score by 11.9 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 Blueair - Blue Pure 311i+ Max if…
Blueair - Blue Pure 311i+ Max has the measurable edge on noise db min.
Choose Dyson - Purifier Big+Quiet Formaldehyde if…
Dyson - Purifier Big+Quiet Formaldehyde has the measurable edge on coverage m2, cadr m3h.
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 Blueair - Blue Pure 311i+ Max wins
- ▲Min noise — 1.00 dB less. 23 vs 24.
Why Dyson - Purifier Big+Quiet Formaldehyde wins
- ▲Coverage — 185.71% more. 100 m² vs 35 m².
- ▲CADR — 28.00% more. 640 m³/h vs 500 m³/h.
Spec comparison
Performance
| Spec | Blueair - Blue Pure 311i+ Max | Dyson - Purifier Big+Quiet Formaldehyde |
|---|---|---|
| CADR | 500 m³/h | 640 m³/hlead |
| Coverage | 35 m² | 100 m²lead |
| True HEPA H13+ | true | true |
| Activated carbon | true | true |
Smart & Noise
| Spec | Blueair - Blue Pure 311i+ Max | Dyson - Purifier Big+Quiet Formaldehyde |
|---|---|---|
| Min noise | 23 dBlead | 24 dB |
| Air quality sensor | true | true |
| Smart app | true | true |