Air purifier · whole-room
Coway Airmega 400
A dual-intake powerhouse rated for 1,560 sq ft with high CADR and pure mechanical filtration - no ionizer, no ozone.
Flags
- · Claimed room size exceeds what the unit's AHAM CADR can deliver.
Flags indicate missing certifications or data gaps under our rubric, not a confirmed finding that a product fails to perform.
Total cost of ownership
- Annual filters
- $129/yr
- Device
- $649
- 5-year total
- $1294
Certifications
- ANSI/AHAM AC-1smoke, dust, pollen
Overview
The Coway Airmega 400 is a whole-house air purifier built around a True HEPA filter. Its Clean Air Delivery Rate is AHAM-verified at 400 cfm, and it uses no ionizer and no ozone-generating stage. Filters run about $129 per year, on the expensive end to run.
By the numbers
- Clean Air Delivery Rate
- 400 cfm (AHAM-verified)
- Real coverage at 4.8 ACH
- ~620 sq ft
- Manufacturer room claim
- 1560 sq ft (a ~2 ACH figure; larger than its CADR supports)
- Filter
- True HEPA
- Ozone / ionizer
- no ionizer and no ozone-generating stage
- Noise (low)
- 22 dBA
- Power draw
- 66 W
- Annual filter cost
- $129/yr
- 5-year cost of ownership
- $1294 (device + filters)
- Certifications
- ANSI/AHAM AC-1
Strengths
- + Safety: 8.0/10
- + Practical Fit: 8.0/10
Watch-outs
- - Verified Performance: 3.0/10
- - Total Cost of Ownership: 1.0/10
- - Certification: 3.0/10
- - Claimed room size exceeds what the unit's AHAM CADR can deliver.
Who it is for
- · Large living rooms and open-plan spaces
- · Anyone sensitive to ozone, or with asthma or allergies
- · Light sleepers - it is near-silent on its lowest setting
Who should skip it
- · Large rooms - its real coverage is smaller than the box claims
- · Buyers focused on low running cost - filters are pricey
What to know before buying
- · The 400 uses two Max2 filter sets (part AP-2015-FP), one on each side, with a stated lifespan of about 12 months, so each replacement cycle means buying a pair.
- · AHAM-verified coverage is 1,560 sq ft at 2 air changes per hour; measured noise runs from about 22 dB on the lowest setting to roughly 52 dB on the highest.
- · The unit weighs about 24.7 lbs and measures roughly 14.8 x 22.8 x 14.8 inches, so it occupies meaningful floor space.
How it scored
Verified Performance
3.0/10 · 30%AHAM CADR, true sealed HEPA, air changes per hour, honest room-size match.
- +3AHAM Verifide CADR published A400 cfm (AHAM Verifide) - CADR is third-party verified by AHAM, not a manufacturer claim.
Total Cost of Ownership
1.0/10 · 25%Computed annual filter cost vs the room-size class median. The number nobody surfaces.
- 0Annual filter cost vs class median A$129.00/yr (above class median (expensive to run)) - Computed annual filter cost scored against the room-size class median.
- +1Washable pre-filter Bwashable pre-filter - A washable pre-filter extends main-filter life and lowers running cost.
Certification
3.0/10 · 15%AHAM Verifide, Energy Star, CARB, published lab efficiency.
- +3Published lab-tested efficiency AAHAM-listed CADR - Filtration performance is independently lab-tested and published.
Safety
8.0/10 · 15%Ozone and ionizer behavior. Ozone generators hard-fail.
- +8No ozone-generating technology Ano ionizer / no ozone - No ionizer, plasma, or ozone-emitting stage.
Practical Fit
8.0/10 · 15%Noise, filter-change indicator, energy draw. Smart features are neutral.
- +4Quiet at low speed B22 dBA low - Runs at 50 dBA or quieter on its lowest useful speed.
- +2Filter-change indicator Bindicator present - Tells you when the filter actually needs replacing.
- +2Energy draw disclosed B66 W - Discloses power draw at a standard speed.
- ·Smart features (neutral) Capp / auto mode - App control and auto mode are neither rewarded nor penalized.
FAQ
- How often do I replace the filters and how many do I buy?
- Coway rates the Max2 filters for about 12 months, and because the 400 holds one set on each side you replace two at a time. The washable pre-filters are cleaned rather than replaced.
- What size room is the Airmega 400 rated for?
- Coway lists 1,560 sq ft at 2 air changes per hour. At the stronger 4.8 air changes per hour we score against, its real coverage is much smaller.
Related guides
This score is our opinion under our published rubric, not a statement of objective fact or a lab test of this product. We score what third-party certifications prove; absence of a certification means we found no verification, not that a product fails to perform. Last reviewed 2026-06-01. Scored under air-v1.0. Prices and certifications are re-verified on a cadence; see the methodology for how each rule fires.