Buy the Coway Mighty (AP-1512HH) for a bedroom or a living room up to about 360 sq ft; it's the cheaper machine to buy and to keep. Buy the Blueair Blue Pure 211i Max for a space of roughly 400 to 670 sq ft, or if you want an app. The Blueair moves nearly twice the air (435 vs 233 CFM smoke CADR), but its ionizing stage is always on, while the Mighty's can be switched off.
The short answer
Choose the Coway Airmega AP-1512HH Mighty if the room is a bedroom, office or modest living room, you want the lowest three-year cost, and you'd rather control a purifier with buttons than an app.
Choose the Blueair Blue Pure 211i Max if the space is open-plan or above about 400 sq ft, you want schedules, phone alerts or Alexa and Google control, and an always-on ionizing stage doesn't bother you.
| On paper | Coway Mighty (AP-1512HH) | Blueair Blue Pure 211i Max |
|---|---|---|
| Smoke / dust / pollen CADR | 233 / 246 / 240 CFM | 435 / 452 / 450 CFM |
| Room size at 4.8 air changes/hr | ~361 sq ft | ~674 sq ft |
| Rated noise | 24.4 to 53.8 dB | 23 to 53 dB |
| Rated maximum power | 77 W | 46 W |
| Size (W x D x H) | 16.8 x 9.6 x 18.3 in | 14.4 x 14.4 x 22.7 in |
| Weight | 12.3 lb | 16.2 lb |
| Ionizer | Yes, switchable | HEPASilent, always on |
| Sensor | Dust sensor, 3-color lamp | PM1, PM2.5, PM10 |
| App and voice | None | Blueair app, Alexa, Google |
| Genuine filters | AP-1512HH-FP set, $56.99 to $59.79 a year | $69.99 every 6 to 9 months |
| Typical price | $220 to $250 | $230 to $350 ($349.99 list) |
| Warranty | 3 years motor and electronics, 1 year other parts | 1 year; 3 years if registered within 60 days |
Room by room
Air changes per hour equal CADR times 60, divided by the room's volume. With 8 ft ceilings and each unit on its top speed:
| Room | Mighty | 211i Max |
|---|---|---|
| 12 x 14 bedroom (168 sq ft) | 10.4 per hour | 19.4 |
| 15 x 20 living room (300 sq ft) | 5.8 | 10.9 |
| 18 x 24 open plan (432 sq ft) | 4.0, short of 4.8 | 7.6 |
| 24 x 26 kitchen and lounge (624 sq ft) | 2.8 | 5.2 |
The Mighty runs out of headroom a little past 360 sq ft. The Blueair still clears a 624 sq ft open plan at a proper rate. A 9 ft ceiling trims both limits by about 11%, to roughly 321 and 599 sq ft; the room size calculator handles other ceiling heights.
Where the Blueair's extra airflow pays off
Giving that 15 x 20 ft living room 4.8 changes an hour takes about 192 CFM. That is 82% of the Mighty's maximum, so it will sit near speed 3 whenever the air is dirty. The same 192 CFM is 44% of the Blueair's output, which leaves it on a gentler setting.
So the rated noise ranges, which look almost identical, don't tell the whole story. In a room near the Mighty's limit, the Blueair delivers the same cleaning at a lower, quieter speed. In a 12 x 14 bedroom the advantage disappears: the Mighty has plenty in reserve there too, and the Blueair's spare capacity is money spent on air the room doesn't need.
Three-year cost
Assumptions: Mighty at $235 (mid-range price); Blueair at its $349.99 list and at a $230 sale price; first filters come in the box; Mighty filter sets at $59.79 once a year; Blueair's standard $69.99 filter at its 9-month rating or the 6-month pace its own FAQ allows. Electricity is listed separately because neither maker publishes power draw per speed.
| Over 36 months | Mighty | 211i Max, 9-month filters | 211i Max, 6-month filters |
|---|---|---|---|
| Purchase | ~$235 | $349.99 | $349.99 |
| Filters | 2 x $59.79 = ~$120 | 3 x $69.99 = ~$210 | 5 x $69.99 = ~$350 |
| Total before power | ~$355 | ~$560 | ~$700 |
| Same, Blueair bought at ~$230 | ~$440 | ~$580 | |
| Power ceiling (max draw, 24/7, $0.17/kWh) | ~$115 a year | ~$69 a year | ~$69 a year |
Even with the Blueair on sale, the Mighty stays about $85 to $225 cheaper over three years. The Blueair's efficiency claws some back: per CFM of smoke CADR, it uses about a third of the Mighty's rated wattage at full speed. In daily use on Auto both sit far below those ceilings, so the real electricity gap is smaller. Enter your own speeds and prices in the filter cost calculator.
Differences that matter after the first week
The ionizer. Coway gives the Mighty an Ionizer button with its own indicator, so it can stay off permanently. Blueair's HEPASilent design charges particles before the filter and can't be disabled, and independent reviewers have reported small amounts of ozone from it. If anyone in the home has a firm no-ionizer rule, that settles it; the ionizer safety guide covers how much it matters.
Controls. The Mighty is buttons only: Auto, three speeds, Eco mode that stops the fan in clean air, and a 1, 4 or 8 hour timer. The 211i Max adds the Blueair app, schedules and voice control, which is handy for running it hard before you get home.
Filter routine. The Mighty has two clocks, a carbon sheet at 6 months and a HEPA panel at 12, both in one $57 to $60 box. Its pre-filter is a mesh panel you clean every 2 to 4 weeks. The Blueair is one filter, changed every 6 to 9 months, with a washable fabric sleeve outside. The Mighty filter guide and 211i Max filter guide cover parts and variants.
Shape. The Mighty is a slim box only 9.6 in deep, easy to tuck beside a bed or dresser as long as it keeps the 20 cm (about 8 in) gap to the wall that Coway's manual asks for. The Blueair is a 14.4 in wide cylinder, 4.4 in taller, with its washable fabric sleeve wrapped around the outside.
Warranty. Coway covers the Mighty's motor and electronics for 3 years with no registration step. Blueair starts at 1 year and extends to 3 if you register within 60 days, so put a reminder in your phone the day it arrives.
Which one to buy
Measure the room first. Under about 360 sq ft, the Coway Airmega AP-1512HH Mighty does the job for less money, with an ionizer you can leave off. Between roughly 400 and 670 sq ft, or wherever you want app control, the Blueair Blue Pure 211i Max is the better fit.
If you want a bedroom unit with no ionizer at all, the Coway Airmega Mighty2 drops it entirely and is rated quieter at its lowest speed. If you want big-room airflow with purely mechanical filtration and an app, look at the Levoit Core 600S. For how the two brands compare across their ranges, see Blueair vs Coway.
Frequently asked questions
Is the Blueair 211i Max too big for a bedroom?
Not if you have the floor space. It is 22.7 in tall and 14.4 in square, and in a 12 x 14 ft bedroom it can reach a healthy air-change rate on a low speed. The catch is cost: you pay more up front and more for filters than the Mighty, which already gives that room about 10 air changes an hour at full speed.
Can I turn off the ionizer on either purifier?
On the Coway Mighty, yes: the Ionizer button switches it on and off, and an indicator shows its state. On the Blueair 211i Max, no. Its HEPASilent stage charges particles as part of how the filter works and runs whenever the fan does.
Which one has the better air quality sensor?
On paper, the Blueair. It reports PM1, PM2.5 and PM10 and feeds an app, while Coway describes the Mighty's sensor as a dust sensor driving a three-color lamp. Both use their readings to run an auto mode.
Do they use the same filters as their older siblings?
The Mighty's AP-1512HH-FP set also fits the Airmega 200M, but not the Mighty2. The 211i Max's filters fit only the 211i Max, not the older Blue Pure 211+ or 211+ Auto.
Which one is cheaper to run per year?
The Mighty on filters, at about $57 to $60 a year against $93 to $140 for the Blueair. On electricity the Blueair has the lower ceiling, 46 W against 77 W at full speed, which is worth up to about $46 a year if both ran flat out around the clock.