Coway
Coway Airmega 400
Ranked #3 of 4 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
96
Running Cost25% of score
76
Noise Level15% of score
90
Price Value25% of score
62
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
- $350 is more than double the Mighty for a machine most homes do not need
- Middle-of-pack energy efficiency, so the running cost is above the Levoit
- Physically large — this is a piece of furniture, not an appliance you hide
Where this product appears
Also worth a look
Sources: The Home Picker in-home comparison (2026-06-12) · Consumer Reports air purifier buying guide (2026-06-04)Last checked by Picksights 2026-07-29