Coway Airmega 200M vs 400S (2026)
Buy the 200M for a room up to about 360 sq ft. Spend nearly three times as much on the 400S only for a bigger open-plan space or if you want app control.
Per square foot of coverage, the 400S costs about twice as much as the 200M.
Coway rates the 200M for 361 sq ft at 4.8 air changes an hour; worked out from its smoke CADR, the 400S covers about 510. Below 360 sq ft both units clear the room at that rate, so the extra money buys an app, a low setting 2.4 dB quieter, and one filter set changed about once a year in place of the 200M’s six-month carbon filter. The 200M scores a little higher on Clear Air Living’s rubric, mainly on value for money.
Side-by-Side Specs
| Spec | Coway Airmega 200M | Coway Airmega 400S |
|---|---|---|
| Price | ~$218 Amazon, ~$220 Sylvane | ~$610 Amazon, ~$650 Sylvane |
| Room size at 4.8 ACH | 361 sq ft (Coway) | About 510 sq ft by its CADR (Coway: 1,560 sq ft at 2 ACH, about 650 converted) |
| CADR smoke / dust / pollen | 246 / 249 / 277 | 328 / 328 / 400 |
| Noise, lowest to highest | 24.4 to 55.1 dB | 22 to 52 dB |
| Filters | Pre-filter, deodorization (carbon), True HEPA, plus a bipolar ion device | Washable pre-filter plus Max2 (activated carbon and HEPA) |
| Filter replacement | Deodorization about 6 months, HEPA about 12 months | Max2 set about 1 year |
| Auto Mode | Yes | Yes |
| App control | No | Yes (Wi-Fi) |
| Size and weight | 16.8 x 18.3 x 9.6 in, 12.3 lb | 14.8 x 22.8 x 14.8 in, 24.7 lb |
| Technical score | 4.5 | 4.4 |
| Where to buy | Airmega 200M on Amazon (~$218) Airmega 200M at Sylvane (~$220) | Airmega 400S on Amazon (~$610) Airmega 400S at Sylvane (~$650) |
Room Size Decides It
Run each unit’s smoke CADR, the lowest of its three ratings, through the air-change math with an 8-foot ceiling. The 200M’s 246 CFM cleans a 200 sq ft bedroom about nine times an hour and a 300 sq ft living room about six times. The 400S manages about twelve and eight in the same two rooms. Both clear the 4.8 bar with room to spare, so in either space the 400S’s extra airflow mostly lets it run a speed lower.
The gap opens above 360 sq ft. In a 450 sq ft open kitchen and living room, the 200M falls to about four air changes an hour on high, under the 4.8 that AHAM uses for its room ratings, while the 400S still delivers about five and a half. Between about 360 and 510 sq ft you have two options: one 400S, with one unit and one filter set, or two 200Ms at opposite ends of the room, which deliver more combined airflow for about 70 percent of the price. Past 510 sq ft neither unit reaches 4.8 alone, and a pair of 200Ms is the better buy up to about 770 sq ft.
Why the 400S carries two coverage figures
Coway rates the 200M at 4.8 air changes an hour but the 400S only at two, for 1,560 sq ft. Converted to 4.8, that is about 650 sq ft. Coway does not say which CADR the figure rests on, and at two air changes it implies about 416 CFM, more than the 400S’s 328 smoke rating. This page uses the smoke-based figure, about 510 sq ft with an 8-foot ceiling. Maker ratings do not always match that arithmetic: the same math gives the 200M about 384 sq ft, above Coway’s own 361, so the 200M is listed at Coway’s figure.
Noise and Filter Changes
On paper the 400S is the quieter unit at both ends of its range: 22 dB on its Sleep speed against the 200M’s 24.4, and 52 dB on high against 55.1. Both sets of figures are Coway’s own. In a bedroom the difference on low is small; the bigger effect is that the 400S can hold a room on a lower speed because it moves more air.
The filter routines differ more than the noise. The 200M has two filters on separate schedules: the deodorization filter about every six months and the True HEPA filter about every twelve, with an indicator for each change and for cleaning the pre-filter. The 400S has one Max2 set rated for about a year, behind a washable pre-filter. Filter prices change, so check the current price of each set before you buy.
The 200M includes a bipolar ion device as its fourth stage. Coway’s pages checked for this comparison do not state an ozone figure. If ozone matters to you, check whether the model appears on CARB’s list of certified air cleaning devices, and see the EPA’s page on ionizers.
Both have Auto Mode, which changes fan speed from the unit’s own air quality reading, and both show the reading on an indicator light. Only the 400S connects to an app.
The Two Units
Coway Airmega 200M
For a bedroom or a living room up to about 360 sq ft, the 200M clears the 4.8 air-change mark on its own. Its four stages run from a pre-filter through a deodorization carbon filter and True HEPA to a bipolar ion device, and Auto Mode adjusts the fan from its air quality reading. At 12.3 lb it moves between rooms easily. Skip it if the room is larger or you want phone control.
Coway Airmega 400S
The 400S is built for an open-plan space of 360 to 510 sq ft. Its smoke CADR of 328 and pollen CADR of 400 are 82 and 123 CFM above the 200M’s, and the Wi-Fi app adds schedules and remote checks. The trade-offs are weight and price: it weighs 24.7 lb and costs nearly three times as much as the 200M. Skip it for a single bedroom.
Frequently Asked Questions
Is the Airmega 400S worth it over the 200M for a bedroom?
Usually not. The 200M cleans a 200 sq ft bedroom about nine times an hour on high, well above the 4.8 standard. The 400S is 2.4 dB quieter on low, a small gap at that level, for nearly three times the price. The 400S makes sense in a bedroom only if you want the app, or the bedroom opens into a larger living space you want to clean with one unit.
Can two Airmega 200Ms replace one 400S?
For a large open-plan room, yes, for less money. Two 200Ms together carry 492 CFM of smoke CADR against the 400S’s 328, at about 70 percent of the 400S’s price on Amazon. The trade-off is two units on the floor and two sets of filters to track.
Which one handles pollen better?
The 400S, on its published numbers: a pollen CADR of 400 against the 200M’s 277. In a room the 200M is sized for, both exceed 4.8 air changes an hour for pollen, so the difference shows mainly in larger rooms.