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Appliances · Coway · 2017

Coway Airmega 400

A heavy-duty purifier sized for the large open rooms most portable units quietly cannot handle.

Throughput is cheap in a room nobody sleeps in — #1

Overall

8.0

out of 10

Axis scores

Appliances is scored on these 5 axes. The total is their plain average — nothing is weighted.

Coway Airmega 400 — axis scores out of 10Horizontal bar chart of editorial scores out of 10 across 5 axes. Bars run from a shared zero baseline; longer is better. Coway Airmega 400: Performance 9.0, Value 7.0, Durability 8.4, Ease of use 8.2, Quietness 7.6.PerformanceCoway Airmega 400 — Performance 9.0 out of 109.0ValueCoway Airmega 400 — Value 7.0 out of 107.0DurabilityCoway Airmega 400 — Durability 8.4 out of 108.4Ease of useCoway Airmega 400 — Ease of use 8.2 out of 108.2QuietnessCoway Airmega 400 — Quietness 7.6 out of 107.6Editorial score out of 10 — higher is better
  • Performance — How well it does the core job
  • Value — What the same money buys elsewhere
  • Durability — Failure and fade reports past the one-year mark
  • Ease of use — Setup, daily operation, cleaning, maintenance
  • Quietness — Operating noise — a higher score means quieter

Specs

Coverage
Very large rooms
Filter
Dual intake, HEPA plus carbon
Sensor
Laser particle sensor, four-color indicator

As published by the manufacturer. We didn't measure these ourselves.

Is it for you

Buy it if

  • A room large enough that smaller units cycle constantly
  • You want a sensor-driven auto mode that reacts to the room instead of a fixed speed
  • Dual-sided intake suits where the unit has to sit

Skip it if

  • Proprietary filters that cost real money every six months
  • Floor space is tight — the footprint is substantial

Two filter banks draw air from both sides. That single decision separates this machine from the rest of the comparison and explains how it handles rooms that leave smaller purifiers running flat out all day. Doubling the intake area halves the velocity needed for a given delivery, a quieter and more efficient way to clean a large space than spinning one fan harder.

A laser particle sensor drives the four-color air quality ring, so you watch the machine react instead of trusting that it does. Owners end up learning things about their own homes from it. Cooking pushes the ring red for twenty minutes. Opening a window during traffic hours turns out worse than leaving it shut.

Ownership cost is where the machine loses ground. Filters are proprietary, physically large, and replaced as a pair, and across three years they come to a meaningful fraction of what the unit cost. No third-party supply is worth trusting, so the price is whatever Coway sets.

Footprint deserves the same scrutiny. This is a substantial piece of furniture, not an appliance that disappears into a corner, and drawing from both sides means it wants clearance on both. That rules out the alcove, and it rules out the gap beside a sofa people usually have in mind.

Nothing else here handles a large open-plan space, or a household with real air quality concerns, without compromising somewhere. Put it in a bedroom and it is oversized in every dimension, cost included.

Last updated . The scoring method is on how we rank.