Blueair 211i Max vs 311i Max
Two machines from one range that differ on exactly one axis. Everything a buyer normally weighs comes back a tie, which makes this a measuring job.
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Buy the 311i Max under 439 square feet and the 211i Max above it. The two are identical on measured ozone, ion classification and filter grade, and differ only in certified output — 283 CFM against 435, which the register turns into 439 against 674 certified square feet.
Buyers usually approach this pair as good and better. They are more accurately small and large, and buying the large one for a small room is the most common way to spend money in this category without getting anything for it.
The numbers, side by side
| 311i Max | 211i Max | |
|---|---|---|
| Smoke CADR | 283 CFM | 435 CFM |
| Dust CADR | 314 CFM | 453 CFM |
| Pollen CADR | 365 CFM | 450 CFM |
| PM2.5 CADR | 298 CFM | 444 CFM |
| Certified room size | 439 sq ft | 674 sq ft |
| Power draw | 29.6 W | 44 W |
| Annual energy (certified) | 193 kWh | 256 kWh |
| Electricity per year | $35 | $47 |
| Air per watt | 8.4 CFM/W | 9.0 CFM/W |
| Measured ozone | 2 ppb | 2 ppb |
| Ionizer | Registers disagree | Registers disagree |
| Filter classification | HEPA-Type | HEPA-Type |
Electricity costs on this page use 18.34¢ per kWh, the U.S. average residential price for June 2026 from the U.S. Energy Information Administration, Electric Power Monthly, Table 5.3. Your rate is on your bill and is probably not this one; multiply the kWh figure by your own rate and you have your number.
Where the crossover actually falls
AHAM’s rule asks for a certified smoke CADR of at least two-thirds of the room’s floor area at an eight-foot ceiling. The 311i Max delivers 283, which clears a room of 439 square feet. Above that it drops below the certified rate and the 211i Max becomes the correct machine rather than the bigger one.
| Room | 311i Max | 211i Max | Clears 4.8 ACH? |
|---|---|---|---|
| 250 sq ft | 8.5 ACH | 13.1 ACH | Both, comfortably |
| 350 sq ft | 6.1 ACH | 9.3 ACH | Both |
| 439 sq ft | 4.8 ACH | 7.4 ACH | Both — the 311i exactly |
| 550 sq ft | 3.9 ACH | 5.9 ACH | 211i only |
| 674 sq ft | 3.1 ACH | 4.8 ACH | 211i — exactly |
| 800 sq ft | 2.7 ACH | 4.1 ACH | Neither |
The one wrinkle worth knowing
The 311i Max is not simply a smaller 211i Max on every measure. Its certified pollen CADR is 365 against a smoke figure of 283 — 29% higher, the largest gap between those two columns of any machine we cover. The 211i Max’s pollen figure is only 3% above its smoke figure.
Pollen is the largest of the three test particles, so every machine posts a higher pollen number; the 311i Max just posts a much higher one. If seasonal allergy is the reason you are buying and the room is inside its coverage, the smaller machine is punching above where the headline number puts it — the roundup that ranks on the pollen column goes through why that column is worth reading.
Quick picks
Both sizes, plus the machine that answers the one question neither Blueair does.
| # | Product | Best for | Certified CADR | Price |
|---|---|---|---|---|
| 1 |  Right under 439 sq ft Blueair Blue Pure 311i Max 283 certified CFM on 29.6 watts — the cheapest large coverage to run. | Mid-size rooms on a small electricity bill | 283CFM smoke AHAM VERIFIDE | |
| 2 |  Right above 439 sq ft Blueair Blue Pure 211i Max 435 certified CFM across 674 sq ft at 9.0 CFM per watt. | Open-plan spaces above 500 sq ft | 435CFM smoke AHAM VERIFIDE | |
| 3 |  If the ozone figure is the issue Honeywell HPA6000 257 certified CFM, 0.00 ppb measured, recorded HEPA not HEPA-Type. | Large living rooms, true HEPA | 257CFM smoke AHAM VERIFIDE |
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The picks
Blueair Blue Pure 311i Max
Blueair · model 3332111100 (Blue Pure 311i Max)
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439 certified square feet on under 30 watts. The best power-to-coverage ratio at mid size, with the same ion-generator caveat as the rest of the Max range.
283 smoke / 314 dust / 365 pollen CFM · 298 PM2.5
- Certified room size
- 439 sq ft
- Energy / year
- 193 kWh
- Electricity / year
- $35
- Air per watt
- 8.4 CFM/W
- Power draw
- 29.6 W
- Noise
- Not published
- Measured ozone
- 2 ppb
- Filter class
- HEPA-Type
- AHAM rule, 400 sq ft
- Clears it (267 needed)
Ion generator — fitted
AHAM classifies this model 'Fan Filter with Ion Generator'; ENERGY STAR records 'Fan and Filter' with 2 ppb measured ozone.
283 certified smoke CADR across 439 certified square feet on 29.6 watts — $35 a year, the cheapest large-coverage machine we cover to run. For a bedroom or a closed living room this is the correct size and the 211i Max is headroom you are paying for.
The honest con: the same ion-stage dispute and 2 ppb measured ozone as its larger sibling, a HEPA-Type rather than HEPA filter classification, and no published noise figure or filter schedule.
Blueair Blue Pure 211i Max
Blueair · model 3613111100 (Blue Pure 211i Max)
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The most air per watt of anything here and by some distance the largest certified coverage — 674 square feet. It does carry an ion generator, which is the reason it is not our asthma pick.
435 smoke / 453 dust / 450 pollen CFM · 444 PM2.5
- Certified room size
- 674 sq ft
- Energy / year
- 256 kWh
- Electricity / year
- $47
- Air per watt
- 9 CFM/W
- Power draw
- 44 W
- Noise
- Not published
- Measured ozone
- 2 ppb
- Filter class
- HEPA-Type
Ion generator — fitted
The two registers disagree: AHAM classifies this model 'Fan Filter with Ion Generator' while ENERGY STAR records it as 'Fan and Filter'. ENERGY STAR's measured ozone figure is 2 ppb. We report both rather than picking the flattering one.
435 certified smoke CADR across 674 certified square feet at 9.0 CFM per watt. Not an upgrade — the correct size for an open-plan floor, and still only $47 a year. The full record on it.
The honest con: in a room under 439 square feet you are paying roughly a third more electricity for capacity the room cannot use, and it carries every caveat the 311i Max does.
Honeywell HPA6000
Honeywell · model HPA6000B
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More certified air movement than the HPA4300 for four more watts, and the same zero on ozone. The sensible step up if your room is nearer 400 square feet.
257 smoke / 262 dust / 285 pollen CFM · 259 PM2.5
- Certified room size
- 398 sq ft
- Energy / year
- 207 kWh
- Electricity / year
- $38
- Air per watt
- 7.3 CFM/W
- Power draw
- 34.9 W
- Noise
- Not published
- Measured ozone
- 0 ppb
- Filter class
- HEPA
- AHAM rule, 380 sq ft
- Clears it (254 needed)
Buyer-first: neither Blueair answers the ozone question, and if that is what is holding you up the HPA6000 posts 257 certified smoke CADR across 398 certified square feet with 0.00 ppb measured, no ion stage, and a filter recorded HEPA rather than HEPA-Type — at $38 a year.
The honest con: 7.3 CFM per watt is excellent but still behind both Blueairs, it covers less room than either, and Honeywell publishes no noise figure we could source.
The verdict
Common questions
Should I buy the 211i Max or the 311i Max?
Is the 311i Max powerful enough for a living room?
Which Blueair is better for pollen?
Do they use the same filters?
Sources
- AHAM VERIFIDE directory of certified room air cleaners
- ENERGY STAR certified room air cleaners database
- AHAM — air filtration standards and the two-thirds rule
Figures were read on the dates shown against each source. If one has changed, or if we have got something wrong, tell us and we will correct the page.
Read next
- Room sizeBlueair Blue Pure 211i Max ReviewThe highest certified output and the best air per watt on this site, against 2 ppb measured ozone and an ion stage the registers disagree about.
- Room sizeAir purifier size calculatorEnter your room dimensions and get the minimum certified CADR, with the arithmetic shown.
- Room sizeLEVOIT Core 400S vs Core 600SIdentical on ozone, ionizer and filter class. Separated only by 231 CFM against 391 — and the crossover lands at 358 sq ft.