Air Purifiers · Comparison

Coway Airmega 400 vs Honeywell HPA300

This isn't a better-versus-worse comparison — each one is built for a different problem. Per its own bestFor tag, the Airmega 400 is "best for large rooms": 350 CADR with a rated coverage of 1,560 sq ft, the only machine in our ranking genuinely sized for open-plan living. The HPA300 is "best for smoke": a smoke CADR of 300, the highest under $250, even though our formula ranks it last overall on running cost, power draw and noise.

Last updated 2026-07-29.

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Quick comparison

Ranked by Picksights Score. Prices are approximate and change frequently.
Product	Picksights Score	From	Best for
#1 · Coway Coway Airmega 400	8.2/10	$350	Best for large rooms
#2 · Honeywell Honeywell HPA300	7.8/10	$249	Best for smoke

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Top pick

Coway

Number 1: Coway Airmega 400

PS8.2/10

Best for large rooms

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.

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

From $350Approximate — prices change

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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

Honeywell

Number 2: Honeywell HPA300

PS7.8/10

Best for smoke

Our formula ranks it last and it is still the machine to buy for one specific situation. Nothing else here clears smoke as fast, which during a wildfire season is the only figure that matters. What drags it down is what happens the other fifty weeks: two consumables instead of one, over 100W at full tilt and real noise. Buy it if you have smoke events; buy the Levoit if you have a bedroom.

Pros

The highest smoke CADR under $250 — it clears a room faster than anything else here
Long-standing recommendations from allergy organisations
Certified True HEPA at 99.97% of particles at 0.3 microns

Cons

A separate pre-filter every three to four months on top of the annual HEPA — two consumables instead of one
Over 100W at full speed, notably more power-hungry than newer machines
The loudest unit in this ranking, and it has no app or smart controls

From $249Approximate — prices change

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Sources: Consumer Reports (laboratory testing, annual running-cost estimates) (2026-07) · Consumer Reports air purifier buying guide (2026-06-04)Last checked by Picksights 2026-07-29

The real question: room size or smoke events?

The EPA's rule of thumb is a CADR of at least two-thirds of the floor area. On that basis, the Airmega 400 is the only unit in our entire ranking that genuinely serves a large open-plan space: its 350 CADR covers up to 1,560 sq ft. In a normal bedroom, that capacity is airflow you won't use, and its running cost is higher than the category's smaller models.

The HPA300, by contrast, exists for one specific situation: nothing in our ranking clears smoke as fast, with a smoke CADR of 300 that's the highest under $250. The cost is a pre-filter that needs replacing every 3-4 months on top of the annual HEPA, over 100W of power draw at full speed, and the loudest unit in the lineup. Buy it for smoke events; buy the Airmega 400 if what you need to cover is a large open-plan floor.

How we rank

Picksights Score is a weighted average of 4 criteria, the same as in the full air purifier ranking:

Clean air delivery (CADR) — 35%
Running cost — 25%
Noise level — 15%
Price-to-value — 25%

Full ranking: Best Air Purifier →

In depth: Full Coway Airmega 400 review →

Also see: Levoit Core 400S vs Coway Airmega AP-1512HH →

Also see: Levoit Core 400S vs Honeywell HPA300 →