The Blue Pure 311i+ Max shows as currently unavailable, and no Amazon listing for the AirDoctor 3500i could be found. Current prices were checked on Amazon on October 16, 2026. CADR and coverage figures come from the older page and were not retested. The old off-brand filter link was replaced with a genuine Blueair filter.
The Blueair Blue Pure 311i+ Max and the AirDoctor 3500i are two Wi-Fi towers for a large room. Here is how they compare, what changed and which one is worth it.
Table of Contents
Blue Pure 311i+ Max vs AirDoctor 3500i at a Glance
Both are Wi-Fi towers for a large room. The Blue Pure 311i+ Max shows as currently unavailable on Amazon, with 573 ratings at 4.3 stars, and its listing claims 2,232 square feet in an hour. The newer Blue Pure 311i Max is $169.99. The AirDoctor AD3500 is $559.00 on Amazon, and the Wi-Fi AD3500i has no Amazon listing that could be found.
Design
The AirDoctor has a classic white body with rounded corners. The Blueair is the more modern of the two: a fabric cover that doubles as a washable pre-filter, in a choice of colors, with air entering from all sides and leaving through the top. The older page said the Blueair has five washable pre-filter choices.
Performance
The older page gave the 311+ Max a CADR of 300 CFM, which fits 446 square feet at five air changes an hour and 1,116 square feet at two. It gave the AD3500i a CADR of 326 CFM, which fits 510 square feet at five and 1,276 at two. The math holds: 300 CFM clears a 446 square foot room, 3,568 cubic feet, in about 12 minutes. See what CADR means.
Filters
- Blueair. A washable fabric pre-filter, a HEPASilent filter rated at 99.97 percent down to 0.1 microns and a thin carbon layer.
- AirDoctor. A pre-filter, a thick carbon and VOC filter and an UltraHEPA filter rated by the maker at 99.99 percent at 0.003 microns. The older page called it 100 times better than standard HEPA, which is the maker claim.
The AirDoctor has an ion setting that can make a little ozone. Keep it off.
Looking ahead, Blueair has renamed its tower, and that matters for this match-up. The Blue Pure 311i+ Max in the older page shows as currently unavailable on Amazon, while the Blue Pure 311i Max is $169.99. The catch is that a buyer can click an old link and land on the wrong model, or on an off-brand filter, as the old filter link did.
4 Large-Room Air Purifiers to Compare
Prices and ratings were checked on Amazon on October 16, 2026.
Price on Amazon: $169.99 | 4.5 stars from 2,575 ratings (checked October 16, 2026)
The Blueair Blue Pure 311i Max is listed for up to 2,107 square feet with Wi-Fi, auto mode and 23 dB quiet filtration. It has a 4.5 rating from over 2,500 ratings.
Price on Amazon: $49.99 | 4.6 stars from 255 ratings (checked October 16, 2026)
The Blueair F3MAX+ filter is the genuine replacement for the 311i+ Max line, with HEPASilent dual filtration and a carbon layer. It has a 4.6 rating from 255 ratings.
Price on Amazon: $559.00 | 4.7 stars from 485 ratings (checked October 16, 2026)
The AirDoctor AD3500 is listed with UltraHEPA filtration and cleaning 630 square feet in 15 minutes. It has a 4.7 rating from 485 ratings.
Price on Amazon: $179.99 | 4.6 stars from 32,435 ratings (checked October 16, 2026)
The Winix 5510 is listed for up to 1,881 square feet in one hour with true HEPA, a carbon filter and app support. It has a 4.6 rating from over 32,000 ratings.
The risk to watch is the filter fit. The old filter link on this page opened an off-brand replacement. Genuine Blueair filters, such as the F3MAX+ at $49.99, are the safer buy for a unit this price. Expect more third-party filters in the same shape. Check the model on the label, and note that the AirDoctor AD3500i adds Wi-Fi over the AD3500 for more money.
Noise and Power
The older page said the Blueair is quieter and uses less power than the AirDoctor. The 311i Max listing gives 23 dB on low. The AirDoctor runs from 11 to 110 watts and reaches about 59 dB on high, per outside tests.
Which Is Better?
The AirDoctor has the stronger filter claim and thicker carbon. The Blueair is quieter, uses less power and costs about a third as much. For most large rooms, the Blueair is the better value. Read the air purifier filter replacement cost guide before you buy either, and see air purifiers for large rooms.
FAQ
Is the Blue Pure 311i+ Max still sold on Amazon?
It shows as currently unavailable as of October 16, 2026. The Blue Pure 311i Max is $169.99.
How big a room do they clean?
About 446 square feet for the Blueair and 510 for the AirDoctor at five air changes an hour, per the older page.
Which filter should you buy?
A genuine Blueair filter, such as the F3MAX+ at $49.99. The old link opened an off-brand filter.
Which is quieter?
The Blueair, per the older page and the 23 dB listing.
Final Word
The Blueair gets you most of the way for a third of the price. The AirDoctor is for buyers who want its thicker carbon and filter claim.
What happens next: expect Blueair to keep its washable pre-filters and push the 311i line, and AirDoctor to push app control. At $559.00 against $169.99, the price gap is the story.
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