A Blueair Blue Pure 211+ that still runs in a space of 540 sq ft or less is worth keeping: the newer model won't cut your filter spending, and its power savings can't pay back the purchase. If you are buying fresh, get the Blueair Blue Pure 211i Max, which Blueair now sells in the 211+'s place and which adds auto mode, an app and about 24% more airflow.
The short answer
Choose the 211i Max if you are buying new, your open-plan space falls between roughly 540 and 674 sq ft, you want the purifier to ramp up on its own when someone cooks or pollen blows in, or your 211+ has died.
Keep the 211+ if it still runs, the room fits inside its coverage, and you like a machine with one button and nothing to configure. Filters for it are still on sale.
| On paper | Blue Pure 211+ | Blue Pure 211i Max |
|---|---|---|
| Smoke / dust / pollen CADR | 350 / 350 / 350 CFM | 435 / 452 / 450 CFM |
| Coverage at 4.8 air changes an hour | ~540 sq ft | ~674 sq ft |
| Noise, low to high (published) | 31 to 56 dB | 23 to 53 dB |
| Maximum power | 61 W | 46 W |
| Controls | One button, three speeds | Four speeds plus Auto and Night |
| Particle sensing | None | PM1, PM2.5 and PM10 |
| App and voice | No | Blueair app, Alexa, Google Assistant |
| Main filter | 211+ Particle + Carbon, about 6 months | F2MAX Particle + Carbon, $69.99, up to 9 months |
| Yearly filter spend | ~$105 | ~$93 to $140 |
| Status and price | Discontinued | $349.99 list, seen at $227.99 |
What the extra 85 CFM changes in a real room
The jump from 350 to 435 CFM of smoke CADR adds roughly 134 sq ft of coverage at the 4.8 air-change standard. Whether that matters depends entirely on your floor plan.
- 15 x 20 ft living room (300 sq ft, 8 ft ceiling): the 211+ delivers about 8.8 air changes an hour on top speed and the 211i Max about 10.9. Both have room to spare, so the upgrade buys a lower, quieter setting rather than cleaner air.
- 20 x 30 ft great room (600 sq ft): the 211+ falls short at about 4.4 air changes, while the 211i Max manages about 5.4. This is the case where the new model does a job the old one can't.
- 9 ft ceilings: coverage shrinks to about 480 sq ft for the 211+ and about 599 sq ft for the 211i Max.
Plug in your own dimensions with the air changes per hour calculator. If a 211i Max box in your hallway says 410 CFM and about 635 sq ft, that is the pre-update rating; Blueair's product page explains the newer figures follow updated DOE standards.
Auto mode is the upgrade you will notice
The 211+ has no sensor at all. It runs at whichever of its three speeds you last picked, so a burnt pan gets the same airflow as an empty, clean room unless someone walks over and presses the button.
The 211i Max reads PM1, PM2.5 and PM10 and adjusts its fan to match. Its filter warning also works differently: Blueair's RealTrack estimate weighs fan speed, running hours and pollution levels, so the light won't arrive on the fixed six-month rhythm that 211+ owners are used to.
The app adds schedules, air-quality history and Alexa or Google control. Apple Home and Matter are missing, which AppleInsider flagged in its review. Reviewers describe Night mode as the lowest fan speed with the lights fully dimmed. In owner reviews, a recurring gripe is that Wi-Fi pairing can take two attempts on some routers. None of this is compulsory, though: a 211+ owner who never wants to open an app can run the new unit from its own button.
Different filters, similar yearly bill
The two filters do not cross over in either direction. The F2MAX range fits only the 211i Max, and the Blueair Blue Pure 211+ Particle + Carbon Filter fits the 211+ (and Blueair excludes the 211 and 211+ Auto from F2MAX fitment as well).
What surprises upgraders is how little the yearly cost moves. The site's catalog puts 211+ filters at about $105 a year on a six-month cycle. The standard Blueair 211i Max Replacement Filter is $69.99 and rated for up to nine months, which works out to about $93 a year at the full interval and about $140 at six months, the short end of the six-to-nine-month range in Blueair's Blue Pure Max FAQ. Over three years that is roughly $315 for the 211+ against $210 to $350 for the 211i Max. Call it a draw.
The new model does give you more choice. Blueair sells the 211i Max filter in four versions: the standard Particle + Carbon, SmokeBlock ($84.99, with twice the activated carbon), AllergenBlock ($89.99, with an allergen-neutralizing coating) and EcoLast ($99.99, wool-based media Blueair claims lasts twice as long). For a wildfire-prone area, SmokeBlock is the version worth the extra $15.
Spare 211+ filters in the cupboard are a reason to keep the old unit running in a second room rather than listing it for sale.
Can lower power pay for the switch?
No. At the rated maximums, 61 W around the clock comes to about $91 a year at $0.17/kWh, and 46 W to about $69. That $22 gap is the most you could save, because neither model has published per-speed wattage, and at the low speeds most people use the difference shrinks. Even at the $227.99 sale price, payback would take over a decade.
The efficiency itself is real: on paper the 211i Max moves about 9.5 CFM per watt against the 211+'s 5.7. It just isn't worth much money. Test your own hours with the running cost calculator.
The ionizer question doesn't change
Both machines are built on HEPASilent, Blueair's approach of electrostatically charging particles so a looser filter can catch them. On the 211i Max, RTINGS and HouseFresh report that this stage produces small amounts of ozone and cannot be switched off. Swapping one Blueair for the other leaves that trade-off exactly where it was.
If that is your real objection, change brands: the Levoit Core 600S is purely mechanical, rated at 391 CFM (about 606 sq ft), with filters around $60 a year.
When a 211+ owner should upgrade
- You moved or knocked through a wall and now have 540 to 674 sq ft to clean.
- You want the purifier to react without you: allergy season, a gas range, or kids who leave the back door open.
- The 211+ has failed. The 211i Max is the direct successor, and registering it within 60 days stretches Blueair's warranty from one year to three.
Upgrading to save money, or to quiet a bedroom the 211+ already handles on low, makes little sense.
Which one to buy
New buyers should take the 211i Max. If a store still lists a 211+ near the $280 to $320 it sold for earlier this year, the newer model on sale is both cheaper and more capable. Owners with a healthy 211+ in a room that fits it can wait until it breaks.
Shopping for a smaller room, up to roughly 440 sq ft? Blueair's own step down, the Blueair Blue Pure 311i Max, lists at $229.99 and takes a $44.99 filter. And if your space is larger than about 674 sq ft, neither 211 is enough on its own; two smaller units in separate zones usually beat one undersized tower.
Frequently asked questions
Is the Blueair Blue Pure 211+ discontinued?
Yes. In Blueair's support spec table the 211+ is marked discontinued, with the 211i Max shown as the model that took over. Replacement filters for the 211+ remain on sale, so an existing unit isn't orphaned.
Can I put my 211+ fabric pre-filter on a 211i Max?
Blueair doesn't say they cross over, and it sells a separate 211i Max pre-filter for $12.99 in five colors. Order the sleeve named for your model rather than gambling on the old one.
Do I need the app to use a 211i Max?
No. Blueair lists Auto and Night alongside the four fan speeds, and the fan-speed button on the unit is also how you reset the filter light. The app adds schedules, air-quality history and Alexa or Google control.
Will a 211i Max filter fit the 211+ Auto?
No. Blueair says the F2MAX family fits only the Blue Pure 211i Max, and its genuine Amazon listing spells out that it does not fit the 211+ or 211+ Auto.
Why does my 211i Max box say 410 CFM instead of 435?
Blueair re-rated its CADR and room-size figures to newer DOE standards, and older packaging still carries the earlier 410 CFM and about 635 sq ft. It is the same machine, and either figure is well above the 211+'s 350 CFM.