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.
Bottom line
In our scoring the Coway Airmega 400 earns 4.0/10, a weak result, and it stands out on safety (8.0/10). On the data, its 400 cfm CADR is AHAM-verified. Filters run about $129 a year (~$1294 over five years with the device), on the expensive end to run. Our main catch: claimed room size exceeds what the unit's AHAM CADR can deliver.
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.
Where to buy
No buy link on this one: it scored Limited under our rubric, and we only link products we would shortlist ourselves.
Total cost of ownership
Checked 42 days ago- Annual filters
- $129/yr
- Device
- $649
- 5-year total
- $1294
Certifications
- ANSI/AHAM AC-1smoke, dust, pollen
Filters only protect you on their swap schedule. Get an email reminder when this one is due - one note around swap time, nothing else.
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
- Is the Coway Airmega 400's CADR AHAM-verified, and does it emit ozone?
- Its 400 cfm Clean Air Delivery Rate is AHAM-verified - independently tested, not a box claim. It has no ionizer and no ozone-generating stage.
- 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.
Compared head-to-head
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 were last checked 42 days ago; the freshness chip above the cost panel shows the current state. See the methodology for how each rule fires.