Coway

Coway Airmega 400

Name: Coway Airmega 400
Brand: Coway

Updated 2026-07-291 min read2 sources cited

PS8.2/10

Ranked #3 of 5 in Best Air Purifier

Best for large rooms

From $350Approximate — prices change and we do not track them in real time

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Key specifications

CADR: 350 CFM
Rated coverage: 1,560 sq ft
Filtration: 4-stage with washable pre-filter and H13 True HEPA
Efficiency: ENERGY STAR certified

Our verdict

Buy this only if you have measured your room and the smaller machines do not cover it. The EPA guideline is a CADR of at least two-thirds of the floor area, and on that basis this is the only unit here that serves a genuinely open-plan space. In a bedroom it is an expensive way to buy airflow you cannot use, and its running cost is higher than the Levoit's. Size the machine to the room first; everything else is secondary.

How it scores

Each criterion is scored 0-100 from published specs and lab-tested figures in the sources below, then weighted by the fixed formula this category uses. The weights are the same for every product here.

Clean Air Delivery35% of score

Running Cost25% of score

Noise Level15% of score

Price Value25% of score

Strengths and limitations

Pros

The only machine here with the airflow to actually serve an open-plan floor rather than one room
Quiet on low despite moving far more air than the rest of this ranking
Washable pre-filter, as across the Coway line

Cons