Coway Airmega 400: Specs, Price, Pros & Cons
This review measures the Coway Airmega 400 against the full 22-spec sheet we track for Air Purifiers, comparing it like for like with the 31 other models in our database. It earns a VS Score of 57 out of 100 — the weighted result of every verified specification measured against the class average.
On the spec sheet it is strongest in filtration and weakest in design. Its clearest single advantage over the class average: a much higher CADR (smoke) — 328 CFM vs 212.72 CFM (avg). Street prices currently start at $ 388.99 for the Coway Airmega 400.
Category strengths
Where the Coway Airmega 400 beats the average
- A much higher CADR (smoke) ?328 CFM vs 212.72 CFM (avg)
- A much higher coverage area ?508 sq ft vs 333.52 sq ft (avg)
- Has true HEPA filter ?
- Has washable pre-filter ?
- Has air quality sensor ?
- Has auto mode ?
- Has activated carbon filter ?
- Has timer ?
- Has sleep mode ?
- A slightly lower min noise level ?22 dB vs 22.26 dB (avg)
Where the Coway Airmega 400 trails the average
- A much lower air changes per hour ?2 vs 4.7 (avg)
- A much heavier build ?11.2 kg vs 5.29 kg (avg)
- No app control ?
- A lower filter life ?12 months vs 16.24 months (avg)
- No voice assistant ?
- A higher power consumption ?66 W vs 50.21 W (avg)
- Fewer filtration stages ?3 vs 3.56 (avg)
- A slightly higher max noise level ?52 dB vs 51.74 dB (avg)
Editor’s note
The Airmega 400 is Coway answering one specific brief: clean a genuinely large space properly, not nominally. Its coverage claim of 1,560 sq ft is quoted at two air changes per hour — a real cleaning rate — where most rivals inflate their numbers by quoting a single air change. Back it with a 328 CFM smoke CADR and you have one of the few consumer purifiers honestly sized for an open-plan living area rather than a bedroom.
The design brief is set-and-forget. A washable pre-filter catches the big stuff; the Max2 combo filter (activated carbon plus Coway's Green True HEPA media) is a single annual replacement; and the auto mode leans on a real-time particle sensor with a colour ring that tells you at a glance what your air is doing. The floor noise of 22 dB is remarkably quiet for a unit this size, and peak power draw is a modest 66 watts.
Know what you're not getting. This is the non-smart 400: no Wi-Fi, no app, no voice control — Coway reserves those for the 400S, about a hundred dollars more at list. The timer is fixed presets (1, 4, 8 hours). And it's a presence in the room: over 11 kilograms and nearly 58 cm tall, with an annual filter set as a recurring cost.
One data note: Coway's current spec sheet says 328/328/400 CADR while older listings still circulate 350/340/350 — we've used the official current figures.
At its frequent ~$390 street price I'd call it the default answer for big-room purification. If your rooms are normal-sized, the Coway Airmega 200M does the same philosophy for a third of the money; if you insist on app control, the 400S exists — but paying more for Wi-Fi on a machine whose whole point is autonomy feels backwards to me.
Specifications
Quality bars are generated automatically against 31 other air purifiers.
Performance
Clean Air Delivery Rate — how quickly smoke particles are scrubbed from the air.
The room size the purifier is rated to clean effectively.
How many times the air in the rated room is cycled each hour.
The number of filtration layers air passes through.
Filtration
A certified HEPA filter captures 99.97% of 0.3-micron particles.
The HEPA grade of the main filter (e.g. H13).
A carbon layer absorbs odours, smoke and VOCs.
Pellet-based carbon beds absorb more odour than thin coated sheets.
A rinseable pre-filter catches hair and large dust to extend filter life.
How long the main filter lasts before replacement.
Noise & power
The lowest-speed noise output; quieter suits bedrooms.
Noise at full speed; lower is better.
Maximum power draw; lower costs less to run continuously.
A dimmed, near-silent mode for overnight use.
Design
A lighter unit is easier to move between rooms.
The height of the unit.
Smart features
Measures particle levels to show and react to air quality.
Adjusts fan speed automatically based on measured air quality.
Control and monitor it from a phone app.
Works with Alexa and Google Assistant.
Tells you when the filter needs replacing.
Schedule the purifier to switch off automatically.
How the VS Score works — and what it can’t tell you
Every measurable spec is scored against the average of all the Air Purifiers we track: matching the class average scores 50, clearly beating it climbs towards 100, and each spec counts according to an editorial weight that reflects real-world impact — a battery-capacity gap moves the score far more than a colour-options list. The quality bars on the spec cards above show where this model sits inside the full range for its class, and the overall VS Score rolls every weighted result into one number.
Unknown values are never estimated. A spec this product doesn’t report simply drops out of its scoring — it isn’t penalised with a guess — but a thinner spec sheet does mean a score built on fewer data points, which is why completeness is disclosed under About this data.
Most importantly: a spec-sheet lead is not the same as a better product. Megapixels, gigahertz and benchmark points describe capacity, not experience — image processing, software optimisation, thermals, haptics and ergonomics decide how a device actually feels, and no table captures reliability or long-term support quality. Treat the VS Score as a structured summary of what can be measured, not a substitute for your own priorities.
About this data
- Specifications are compiled from each manufacturer’s official spec sheet, cross-checked against trusted specification databases, and normalised into one schema so identical things are compared identically.
- Specifications last verified August 21, 2026.
- Data completeness: 22 of the 22 specs in this category are verified (100%). Anything we could not verify is shown as Unknown — never estimated — and is excluded from the score.
- Prices and availability come from live retailer feeds via our shopping partners and refresh throughout the day; a missing price means no partner currently lists the product, not that it is discontinued.
- Want the full picture? Our editorial guidelines explain how we research products, weight the scores and stay independent.
- Spotted an error in a spec? Tell us and we will correct the sheet.
Where to buy
Prices and availability may change. Check the retailer before buying. We may earn a commission on purchases.
Price history
Air Purifiers with similar specs to the Coway Airmega 400
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The bottom line
The Coway Airmega 400 earns a VS Score of 57, a solid mid-pack result among the 32 air purifiers we compare here.
- Who it’s for
- Open-plan living areas and big rooms where most purifiers are undersized — its 1,560 sq ft rating is quoted at a genuine 2 air changes per hour, and the single annual combo filter suits people who want zero fiddling.
- Who should look elsewhere
- Bedrooms and normal rooms (it's 11 kg of machine you don't need — the 200M does those for a third of the price), and anyone who wants app or voice control, which Coway reserves for the pricier 400S.
- The trade-off that matters
- Coverage honesty versus footprint: you get rare, truthfully-rated large-room performance, but it arrives as a 58 cm, 11 kg appliance with a $100+ annual filter habit.
- The main alternative
- Coway Airmega 200M — if your largest room is under ~400 sq ft, it delivers the same set-and-forget philosophy and sensor-driven auto mode at a fraction of the cost.
The VS Score is generated automatically from the weighted specifications above, measured against all other air purifiers in our database. Treat it as a shortlisting guide — not a substitute for your own priorities.
