For most open living areas, buy the Blueair Blue Pure 211i Max: it is rated for the same airflow as the Coway Airmega 450 at $149 less list price, and adds an app and a lower power rating. The Coway earns its premium in two cases only: you want no ionizer at all, or the Blueair's filter would need changing every six months in your home, at which point their three-year costs meet.
The short answer
Choose the Blue Pure 211i Max if you want the most big-room airflow per dollar, app schedules or voice control, and a lighter, shorter body, and an always-on ionizing stage is acceptable to you.
Choose the Airmega 450 if your household rules out ionizers, you want one filter swap a year rather than two, or you like having allergy and smoke versions of a once-a-year cartridge.
| On paper | Blue Pure 211i Max | Airmega 450 |
|---|---|---|
| Smoke / dust / pollen CADR | 435 / 452 / 450 CFM | 439 / 445 / 450 CFM |
| Room size at 4.8 air changes/hr | ~674 sq ft | ~680 sq ft |
| Rated noise | 23 to 53 dB | 23.7 to 57.7 dB |
| Rated maximum power | 46 W | 72 W |
| Size | 14.4 x 14.4 x 22.7 in tall | 13 x 13 x 29 in tall |
| Weight | 16.2 lb | 24.9 lb, with wheels |
| Ionizer | HEPASilent, always on | None |
| Sensors | PM1, PM2.5, PM10 | Laser PM1, PM2.5, PM10 |
| App and voice | Blueair app, Alexa, Google | None |
| Main filter | $69.99, 6 to 9 months | $109 to $119, about 12 months |
| Price | $349.99 list; $227.99 at Amazon in Oct 2026 | $499 list; owners report about $350 on sale |
| Warranty | 1 year; 3 when registered within 60 days | 3 years (motor, electronics); 1 year (other parts) |
Same airflow, different price tags
On rated CADR this is a tie. The Coway leads on smoke by 4 CFM, the Blueair leads on dust by 7, and both score 450 for pollen. RTINGS' top-speed PM1 figure for the 211i Max, reported second-hand at about 419 CFM, backs up Blueair's number; no independent CADR test of the 450 turned up.
That leaves price. The gap is $149 at list, and about $122 at the sale prices seen this year. Spending more on the Coway buys features, not cleaner air.
Sizing: two 680 sq ft machines
At top speed with 8 ft ceilings:
- 22 x 26 open kitchen and living area (572 sq ft): about 5.7 air changes an hour for the 211i Max and 5.8 for the 450. Either handles it with some margin.
- 25 x 28 combined living and dining space (700 sq ft): 4.7 for each, a hair under the 4.8 target.
- 10 ft ceilings: rated reach drops to roughly 539 and 544 sq ft.
Quiet output is where the Blueair has the better-documented story. RTINGS reportedly measured about 224 CFM on speed 2 while under 45 dBA, enough to give a 14 x 20 lounge (280 sq ft) about 6 air changes an hour at that volume. No comparable figure exists for the 450; the Trusted Reviews long-term test described a calm low end and a noticeably louder fan beyond speed 1. Your own room's numbers come from the room size calculator.
Three-year cost: where the gap narrows
Assumptions: list prices; the starter filter in the box is used up before any purchase; the 211i Max uses the standard Particle + Carbon filter ($69.99) at Blueair's 9-month rating or the 6-month pace its own FAQ allows; the 450 uses Fresh Starter+ ($109) every 12 months. Electricity is left out of the totals because neither maker publishes power draw per speed.
| Three years | 211i Max, 9-month filters | 211i Max, 6-month filters | Airmega 450 |
|---|---|---|---|
| Purchase | $349.99 | $349.99 | $499 |
| Filters | 3 x $69.99 = $209.97 | 5 x $69.99 = $349.95 | 2 x $109 = $218 |
| Total before power | ~$560 | ~$700 | ~$717 |
So the Blueair's $149 head start shrinks to about $17 if its filter only lasts six months. On sale prices the pattern repeats: about $438 or $578 for the Blueair against about $568 for the Coway.
Smoke filters bring them closer still. SmokeBlock ($84.99) at nine-month changes works out to about $113 a year; Intense Smoke+ at Coway's top filter price of $119 a year is nearly the same.
On electricity, only rated maximums are published. Running flat out around the clock, 46 W costs about $69 a year and 72 W about $107, a $39 gap that shrinks sharply at the low speeds most homes use. Swap in your own filter dates with the filter cost calculator.
What the Coway's extra money buys
- No ionizer. The 450 relies on a pre-filter, True HEPA and carbon. The 211i Max's HEPASilent stage charges particles and cannot be turned off; RTINGS and HouseFresh both note it gives off small amounts of ozone, and no certified ozone figure for the 211i Max was found. The ionizer safety guide covers whether that should worry you.
- One filter change a year. It slides in from the side, so the unit never needs tipping over.
- Wheels. Useful for a 24.9 lb machine, though reviewers found they don't roll on carpet.
- Adjustable sensor sensitivity. Levels 1 to 3, which helped Trusted Reviews when auto mode seemed slow to react.
What the Blueair gives you that the Coway doesn't
- App, schedules and voice. Alexa and Google Assistant work through Blueair's app; Apple Home and Matter do not. The 450 has a 12-hour timer and nothing remote.
- A smaller presence. It is 6.3 in shorter and 8.7 lb lighter.
- A lower power ceiling. 46 W against 72 W at full speed.
- A washable outer sleeve. The fabric pre-filter can be washed; the 450's built-in pre-filter is vacuum-only.
- Fuller warranty coverage once registered. Three years from Blueair after registration, against Coway's one year on parts other than the motor and electronics.
Two Blueair caveats from owner reviews: Wi-Fi setup sometimes takes a second attempt on certain routers, and 211i Max filters are not interchangeable with the older 211+ family.
Which one to buy
The Blueair Blue Pure 211i Max, for most buyers: it matches the Coway's cleaning, costs less up front, and stays cheaper over three years unless its filter wears out at the fastest pace. Choose the Coway Airmega 450 when an ionizer is a deal-breaker or a twice-a-year filter routine sounds like a chore.
If neither suits, the answer depends on the room. For rooms below roughly 550 sq ft, the Coway Airmega 350 keeps Coway's no-ionizer design at 352 CFM for $339 list with a $79 filter. If you want no ionizer and an app in one big-room machine, the Levoit Core 600S, sized for roughly 606 sq ft, does both. For the wider brand picture, see Blueair vs Coway.
Frequently asked questions
Why does some packaging list the 211i Max at 410 CFM?
Blueair updated its ratings when new DOE test rules arrived, and older boxes and listings still show 410 CFM and about 635 sq ft. The current rating is 435 CFM for smoke. It is the same purifier either way.
Can you wash the pre-filter on either one?
On the 211i Max, yes: the outer fabric sleeve is washable, and Blueair sells spares for $12.99. On the Airmega 450, no. Its pre-filter is part of the cartridge, and Coway says to vacuum or wipe it every two to four weeks and never rinse it.
Do Blue Pure 211+ filters fit the 211i Max?
No. The 211i Max uses its own filter family (Particle + Carbon, SmokeBlock, AllergenBlock and EcoLast), and none of them interchange with the older 211+ or 211+ Auto filters. Use up spare 211+ filters before switching.
Which one is quieter?
On the spec sheets, the Blueair: 23 to 53 dB against the Coway's 23.7 to 57.7 dB. RTINGS, as reported second-hand, measured the 211i Max at roughly 34 to 59 dBA. No lab has published comparable readings for the 450, and reviewers describe it as quiet on low but loud from speed 2 upward.
Does the Airmega 450 work with Alexa or Google?
No. It has no Wi-Fi, so there is no app, voice control or remote scheduling, only a panel timer of up to 12 hours. The 211i Max supports Alexa and Google Assistant through Blueair's app, though not Apple Home or Matter.