Blueair 211i Max vs. 311i Max: Which Air Purifier Should You Choose?

The short answer

Buy the Blueair Blue Pure 211i Max for a living room, an open kitchen and living area, or a large bedroom. Buy the 311i Max for a closed bedroom or home office of up to about 440 sq. ft. The two models share the same design, app and filter types. The difference is capacity: the 211i Max is rated for 23% to 54% more clean air depending on the pollutant, and it is taller, wider and twice as heavy.

Specs side by side

All figures come from Blueair’s own product pages, checked October 3, 2026.

How to read the room-size numbers

The recommended room size is the useful number. Blueair’s 674 and 439 sq. ft. figures assume the purifier cleans the room’s air about 4.8 times an hour, the target the Association of Home Appliance Manufacturers (AHAM) uses for room-size ratings. The 30-minute and one-hour figures on the box assume fewer air changes, so they make the purifier look larger than it is for allergy or smoke use.

Smoke CADR is the most demanding rating because smoke particles are the smallest of the three tested. If you are buying for wildfire smoke or a smoker in the house, compare the smoke column: the 211i Max delivers 435 cfm against 283 cfm.

Which room each one fits

Choose the 211i Max when:

• The room is larger than about 440 sq. ft., or it opens onto a kitchen or hallway.
• You want to run the purifier on a low, quiet setting most of the time. A purifier with spare capacity reaches the same air changes at a lower fan speed.
• Smoke is a concern, since its smoke CADR is the larger margin.

Choose the 311i Max when:

• The room is a closed bedroom or office under about 440 sq. ft.
• You want to move it occasionally. At 7.8 lb, it weighs less than half as much as the 211i Max.
• Floor space is tight. It is about 4 inches shorter and 2 inches narrower.

Noise and running cost

Both start at 23 dB on the lowest setting. At maximum, Blueair lists 53 dB for the 211i Max and 50 dB for the 311i Max. Neither figure matters much on its own. What matters is which setting you need to reach the room’s target air changes. In a 400 sq. ft. bedroom, the 311i Max needs close to its top speed to get there, while the 211i Max can run lower. In a small office, the 311i Max is the better match.

Power at top speed is 46 W versus 32 W. Run around the clock at full speed, that is roughly 400 kWh versus 280 kWh a year. Most owners use auto or lower speeds, so real use is usually well under that.

Filters

Each model uses its own size of filter, so filters are not interchangeable between them. Both are offered in three versions: Particle & Carbon (standard), AllergenBlock and SmokeBlock. Blueair estimates filter life at up to 9 months, using an in-app counter that accounts for fan speed, run time and pollution levels.

Frequently Asked Questions

How much more air does the Blueair 211i Max clean than the 311i Max?

Blueair rates the 211i Max at 435 cfm for smoke, 452 for dust and 450 for pollen. The 311i Max is rated at 283, 314 and 365 cfm. For smoke, the hardest of the three, that is about 54% more clean air from the 211i Max.

What room size is each model for?

Blueair recommends the 211i Max for up to 674 sq. ft. and the 311i Max for up to 439 sq. ft., both based on about 4.8 air changes per hour. The larger 30-minute and one-hour coverage figures assume fewer air changes and are not a sizing target.

Is the 211i Max louder?

Both start at 23 dB on their lowest setting. At top speed Blueair lists 53 dB for the 211i Max and 50 dB for the 311i Max. In the same room, the 211i Max can usually run a step lower to deliver the same clean air.

Do they use the same filter?

No. Each model takes its own size of Blueair filter, available in Particle & Carbon, AllergenBlock and SmokeBlock versions. Blueair says each lasts up to 9 months, depending on use.

Sources

• Blueair Blue Pure 211i Max product page
• Blueair Blue Pure 311i Max product page