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The Coway Airmega 400 is the big-room specialist of Coway’s lineup. While the popular Airmega Mighty covers a bedroom, the 400 is built for open-plan living spaces: it is rated for 1,560 square feet, carries an AHAM-verified CADR of 328 for smoke and 400 for pollen, and has been a long-standing pick for large spaces. It is also expensive — list price is around $634 — and it is a big, heavy, boxy unit with no Wi-Fi. This review looks at the verified specifications, the independent coverage math, and the real-world tradeoffs to decide whether the Airmega 400 is worth its price in 2026.
The Short Answer
The Airmega 400 is an excellent large-room air purifier and a poor value at full price. Its dual side-intake Max2 filters, HyperCaptive filtration that captures 99.999% of particles as small as 0.01 microns, and AHAM-verified CADR make it one of the strongest single-unit options for a big open floor. It runs quiet at 22 decibels on low, and the 5-year warranty is among the longest in the category. But the coverage claim needs reading carefully — 1,560 square feet is at 2 air changes per hour, not the 4.8 used by AHAM’s room-size standard — and the replacement filters cost about $130 a year. Buy it on sale, where it often drops to around $370, and it is one of the best large-room purifiers available. Pay full price and you should compare it carefully against two smaller purifiers first.
Key Specifications
| Spec | Detail |
|---|---|
| Model | Coway Airmega 400 (AP-2015F) |
| AHAM CADR | 328 smoke / 328 dust / 400 pollen CFM |
| Coverage | 1,560 sq ft at 2 air changes per hour; 3,120 sq ft at 1 air change per hour |
| Filtration | HyperCaptive: washable pre-filter + activated carbon + True HEPA, dual Max2 filters |
| Particle capture | 99.999% of particles 0.01 microns |
| Noise | 22 dB on low, up to ~52–55 dB on high |
| Fan speeds | 4 (low, medium, high, plus auto/eco/sleep modes) |
| Filter replacement | Max2 filter set about every 12 months, ~$130 |
| Smart features | Air quality sensor, pollution indicator, auto mode, timer |
| Wi-Fi | No (the Airmega 400S adds Wi-Fi and app control) |
| Warranty | 5 years |
| Amazon rating | 4.6 stars from 2,200+ ratings (checked October 2026) |
Filtration: What HyperCaptive Actually Means
The Airmega 400 uses Coway’s HyperCaptive filtration system, a three-stage setup repeated on both sides of the unit. Each side has a washable pre-filter that catches large dust and pet hair, an activated carbon filter that handles odors and gases, and a True HEPA filter that captures fine particles. Coway rates the combined system at 99.999% capture of particles as small as 0.01 microns — finer than the 0.3-micron standard most HEPA filters are rated at. The dual side-intake design is the reason the 400 moves so much air: it pulls from both sides instead of one, which is how a single unit reaches a 400 CFM pollen CADR.
The pre-filters are washable, which extends the life of the more expensive HEPA and carbon stages. The Max2 filter set — the combined HEPA and carbon filters for both sides — needs replacing about once a year and costs roughly $130. Over five years, that is about $650 in filters, which is worth factoring into the total cost before you buy.
CADR and Real Coverage: Read the Fine Print
This is the most important section of this review, because the Airmega 400’s coverage claim is easy to misread. Coway rates the 400 for 1,560 square feet at 2 air changes per hour, and its Amazon listing says up to 3,120 square feet in 60 minutes — one air change per hour. AHAM’s standard room-size calculation uses 4.8 air changes per hour, and at that rate the 328 CFM smoke CADR covers roughly 512 square feet. Independent reviewers have put the realistic room size at about 624 square feet at 5 air changes per hour.
What does that mean in practice? In a 400 to 600 square foot open living area, the Airmega 400 is genuinely excellent — multiple reviewers measured it cutting PM2.5 by 90% in about 8 minutes on high in a 400-square-foot test room. In a 1,500-square-foot open floor, it will still clean the air, but at a much slower rate than the headline number suggests — closer to 2 air changes per hour, which is fine for maintenance but slow for clearing a room after cooking smoke or a wildfire smoke event. If your space is truly 1,500 square feet of open floor, plan on the 400 as your main unit and consider a second purifier, or accept slower clearance. For context on how coverage claims work across brands, our guide to the best air purifiers for large rooms compares the 400 against the alternatives with the same math applied to each.
Noise and Daily Use
The Airmega 400 is quiet where it matters. On low it measures about 22 decibels — effectively silent in a bedroom — and on a middle setting it runs around 39 decibels, quieter than a normal conversation. On high it reaches roughly 52 to 55 decibels, which is noticeable but not intrusive for a large-room purifier moving 400 CFM. The auto mode uses the built-in air quality sensor to ramp the fan up when it detects particles and back down when the air clears, and the sleep mode dims the display and runs the fan at its quietest. The pollution indicator gives a simple color readout of current air quality, which is useful feedback when you are cooking or after you have had the windows open.
The unit is large and heavy — a boxy design that takes up real floor space — so measure before you buy. It needs clearance on both sides for the dual intakes, so it cannot sit tight against a wall or in a corner.
Airmega 400 vs. Airmega 400S
The only meaningful difference between the 400 and the 400S is connectivity. The 400S adds Wi-Fi, app control, and voice assistant support; the standard 400 has no Wi-Fi and no app. Filtration, CADR, coverage, noise, and warranty are identical. If you want to control your purifier from your phone or check air quality remotely, buy the 400S. If you are happy with the onboard controls and auto mode, the standard 400 saves money for the same clean air.
How It Compares
Against the Coway Airmega Mighty AP-1512HH, the 400 is the clear step up for large spaces: the Mighty’s CADR of 233 smoke and 361-square-foot rating suit a bedroom, while the 400’s 328 smoke CADR and dual filters suit an open floor. Against the Levoit Core 600S, the 400 has a higher CADR and a longer warranty, but the Levoit adds Wi-Fi and app control at a lower price. Against the Winix 5500-2, the 400 covers more space and filters more air, but costs substantially more.
For allergy sufferers, the 400’s True HEPA filtration and high pollen CADR of 400 CFM make it a strong choice, and our guide to the best air purifiers for allergies covers how CADR and filter type should drive that decision. If the 400 will live in a bedroom, the noise figures above are encouraging, but our roundup of the best air purifiers for bedrooms focuses on smaller, quieter units that fit a nightstand better — the 400 is overkill for a single bedroom.
Pros and Cons
Pros
- AHAM-verified CADR of 328 smoke / 328 dust / 400 pollen CFM
- HyperCaptive filtration captures 99.999% of particles down to 0.01 microns
- Dual side-intake Max2 filters for high airflow
- Quiet 22 dB low speed with auto, eco, and sleep modes
- Washable pre-filters extend filter life
- 5-year warranty, among the longest available
- 4.6 stars from 2,200+ Amazon ratings
Cons
- Coverage claim is at 2 air changes per hour, not the AHAM standard 4.8
- Replacement Max2 filters cost about $130 per year
- Large, heavy, boxy design needs floor space and side clearance
- No Wi-Fi or app control on the standard 400
- Expensive at full list price around $634
- Noisier than smaller purifiers on high
Frequently Asked Questions
How big a room can the Coway Airmega 400 cover?
Coway rates it for 1,560 square feet at 2 air changes per hour. At the AHAM standard of 4.8 air changes per hour, its 328 CFM smoke CADR covers roughly 512 square feet. In practice it excels in 400 to 600 square foot open spaces and works as a maintenance purifier in larger ones.
How often do you replace the Airmega 400 filters?
The Max2 filter set (HEPA plus carbon for both sides) lasts about 12 months and costs roughly $130. The pre-filters are washable and reusable. The unit has a filter replacement indicator.
Does the Airmega 400 have Wi-Fi?
No. The standard Airmega 400 has no Wi-Fi or app control. The Airmega 400S is the Wi-Fi version, with identical filtration and CADR.
Is the Airmega 400 good for allergies?
Yes. Its True HEPA filtration captures 99.999% of particles as small as 0.01 microns, and its pollen CADR of 400 CFM is among the highest in its class, so it clears pollen and pet dander quickly in a large room.
How loud is the Airmega 400?
About 22 decibels on low, around 39 decibels on medium, and roughly 52 to 55 decibels on high. On auto mode it spends most of its time on the quieter settings.
What is the difference between the Airmega 400 and the Mighty?
The 400 is built for large, open spaces: higher CADR, dual filters, and a much larger coverage rating. The Mighty AP-1512HH is a bedroom and small-room purifier with a 361-square-foot rating and a lower price. Buy the 400 for open floors and the Mighty for bedrooms.
Final Verdict
The Coway Airmega 400 is a genuinely strong large-room air purifier with one flaw: its coverage marketing. Read past the 1,560-square-foot headline, understand that it means 2 air changes per hour, and you will find a purifier with verified CADR, excellent filtration, quiet low-speed operation, and a 5-year warranty that few competitors match. Buy it on sale near $370 and it is one of the best large-room purchases in the category. Pay the full $634 list price and you should think hard about whether two smaller purifiers would serve your space better. Either way, it earns its reputation as the large-room workhorse of Coway’s lineup.