Blueair Blue Pure 211i Max vs Blueair Blue Signature Large (SP4i)
Blueair Blue Signature Large (SP4i)
The short answer
Blueair Blue Signature Large (SP4i) comes out ahead overall with 7.8/10 against 7.4/10 for the Blueair Blue Pure 211i Max. Blueair Blue Pure 211i Max is stronger on indoor-air safety & materials, running cost & ownership and value. Blueair Blue Signature Large (SP4i) is stronger on noise at sleep-usable speeds, cleaning performance for bedroom size and sleep-friendly features. At current verified prices, the Blueair Blue Pure 211i Max costs about $130.00 less.
- Choose the Blueair Blue Pure 211i Max if: Owners of a large primary suite who want high CADR at night without an always-on ionizer, for about $90 less than the SP4i.
- Choose the Blueair Blue Signature Large (SP4i) if: Light sleepers with a large primary bedroom who will pay for the most quiet airflow and accept an always-on ionizer.
Scores by criterion
| Criterion | Blueair Blue Pure 211i Max | Blueair Blue Signature Large (SP4i) |
|---|---|---|
| Noise at sleep-usable speeds | 7.3RTINGS snippet: 33.9 dBA on low; no measured airflow below 45 dB. | 9.3HouseFresh: 229 cfm at 40 dB, 34.8 dB in sleep mode. |
| Cleaning performance for bedroom size | 8.5435 smoke CADR rated. | 9.0455 smoke CADR rated; 229 cfm measured at a quiet 40 dB. |
| Sleep-friendly features | 8.0Night mode with dimmed lights, auto, app. | 8.3Night mode, laser PM2.5 sensor, app. |
| Indoor-air safety & materials | 7.0Zero-ozone verified and CARB; HEPASilent uses electrostatic charging. | 5.0Ionizer cannot be switched off (HouseFresh). |
| Running cost & ownership | 6.546 W; filters last about 9 months. | 5.5About $180 a year in filters (HouseFresh). |
| Value | 6.5$349. | 5.8$439.99 on Amazon. |
Specifications
| Spec | Blueair Blue Pure 211i Max | Blueair Blue Signature Large (SP4i) |
|---|---|---|
| Workflow type | Extra Large Room | — |
| Lowest-speed noise (manufacturer) | 23 dB | 23 dB |
| Top-speed noise (manufacturer) | 53 dB | 55 dB |
| Lowest-speed noise (independent measurement) | 33.9 dBA | 34.8 dBA |
| CADR (smoke where given, else headline) | 435 cfm | 455 cfm |
| Recommended room size (4.8–5 ACH / AHAM) | 674 sq ft | 705 sq ft |
| Max power draw | 46 W | — |
| Sleep / night mode | Yes | Yes |
| App control | Yes | Yes |
| Ionizer / electrostatic stage | HEPASilent (electrostatic charging + mechanical filtration) | Ionizer that cannot be disabled (per HouseFresh) |
| Filter type | HEPASilent particle + carbon filter, washable fabric pre-filter | 7-stage filter incl. pelleted carbon |
| Main filter life | 9 months | — |
| Quiet Mark certified | Yes | — |
Blueair Blue Pure 211i Max
Pros
- Large CADR headroom
- Night mode with dimmed lights
- Zero Ozone Verified per retailers
- Cheaper than the SP4i
- App control
Cons
- Limited independent noise testing
- Oversized for small rooms
- Loud at max, about 58.7 dBA
- Premium price
A sensible big-room alternative to the SP4i if you want to skip the unswitchable ionizer and save some money.
Full Blueair Blue Pure 211i Max review →Blueair Blue Signature Large (SP4i)
Pros
- 34.8 dB in sleep mode
- About 229 cfm at 40 dB
- Large coverage
- App control and PM2.5 sensor
- Doubles as a side table
Cons
- Ionizer cannot be turned off
- Premium price
- About $180 a year in filters
- Tabletop surface scratches easily
The quietest high-airflow option for a big room, but only for buyers who accept the always-on ionizer and the cost.
Full Blueair Blue Signature Large (SP4i) review →Both products are part of our guide The Best Quiet Air Purifiers for Bedrooms of 2026, where you can see every pick, how we score and current prices from each retailer.