Model comparison

Coway Airmega 400 or ProX? Compare room rate and feedback

The Airmega 400 and Airmega ProX are both large Coway purifiers with local controls, sensor-driven Auto and a washable pre-filter in front of a paired Max2 filter set. The practical divide is room rate and feedback: the 400 is the smaller, lighter machine with a color-category signal; the ProX offers more room-area headroom and numeric particle readings, at the price of a far larger, heavier cabinet. Neither model is app-connected.

Compare the same cleaning rate

Coway lists the Airmega 400 for 1,560 square feet at two air changes per hour and 3,120 at one. The manual also gives 780 square feet at four changes per hour. Scaling the two-change figure to 4.8 ACH gives 650 square feet. Coway publishes the ProX at 2,126 square feet at two changes per hour and 4,253 at one; the same rate calculation gives 885 square feet at 4.8 ACH. Those 650- and 885-square-foot figures are calculated comparison values, not printed 4.8-ACH promises. Coway’s manual specifies an eight-foot ceiling for its area basis. Open doors, high ceilings and obstructed airflow can reduce real-room fit.

So the 400 is the more sensible of the pair when its roughly 650-square-foot comparison gives comfortable room margin. If a room is beyond that level or you want more headroom, the ProX is the step up—but not a whole-home guarantee. The 4,253-square-foot one-change figure for the ProX and 3,120-square-foot one-change figure for the 400 are not equivalent to a frequent-cleaning target.

Pick the display you will actually use

The 400 senses particles and changes fan levels in Auto, while the panel shows a four-color air-quality category. It does not display a numeric PM2.5 value. The ProX shows numeric PM1.0, PM2.5 and PM10 readings and color categories on the unit. That makes the ProX a better match if local numeric particle information is an essential choice; it does not make the display a gas or TVOC sensor. Both rely on local controls and both can alter or pause airflow in Auto/Eco/Sleep behavior, so do not read their maximum room ratings as a guarantee that each automatic setting continuously sustains top airflow.

If the app is essential, neither is the answer: Coway explicitly describes the Airmega 400 as not Wi-Fi or app-enabled, and the ProX has no documented app plan. The separately reviewed Levoit Core 600S-P provides app control and a similar 606-square-foot 4.8-ACH comparison area, though the exact airflow basis and controls differ. Consider it when connected scheduling matters more than additional Coway room capacity.

Give the appliance and filters space

The 400’s body is 14.8 × 22.8 × 14.8 inches and 24.7 pounds. The ProX is 18.9 × 36.6 × 24.3 inches and 51 pounds; its four locking wheels help on one level floor, but do not make stairs easy. Both have side intakes and a top outlet that need open airflow. Their two-sided layouts mean each needs routine access on either side and space to remove covers during cleaning.

Each comes with two washable pre-filters and two Max2 filters combining HEPA filtration and activated carbon. The pre-filters can be vacuumed or washed and dried before refitting; the Max2 elements are not washable and are changed as a pair. Coway’s 400 page gives six-to-twelve months in feature copy, one year in its spec table and roughly twelve months in its later filter section; the ProX page also gives a broader six-to-twelve-month statement alongside a one-year specification and manual instruction. Treat the filter indicator and your conditions as more useful than a precise calendar promise, and compare the cost and availability of the exact replacement pair before choosing either machine.

Which one fits your constraints?

• Choose the Airmega 400 when your repeated-cleaning room fits its calculated 650-square-foot comparison, color-only feedback is enough, and you prefer its lighter, shorter body.
• Choose the ProX when you need the higher 885-square-foot calculated comparison or numeric PM1/PM2.5/PM10 readings, and have clear floor space for a 51-pound unit.
• Choose neither for mandatory app control, a confirmed gas/TVOC reading, or a documented pet-specific filter. Carbon filtration and particle feedback are not substitutes.

The exact 400 is a separate, non-Wi-Fi model from the Airmega 400S; do not treat the suffix as a finish change. For either Coway, verify the offered model name, two-sided replacement filter and available space before buying.

Primary references: Coway’s Airmega 400 page and Airmega 300/400-family manual; Coway’s Airmega ProX page and ProX manual.