Coway · Big rooms
Coway Airmega 400
Coway's big two-sided purifier: two sets of carbon and HEPA filters, a smart mode with a live air-quality ring, and a 5-year warranty.
- Filters on both sides
- 5-year warranty
$649.00at cowaymega.com · Nov 2026
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- smoke CADR: clean air it moves each minute
- 376 cfm
- room size it suits, every day
- 54 m²
- 583 ft²
- room size on smoggy days
- 35 m²
- 376 ft²
Coway Airmega 400 at a glance
- Smoke CADR
- 376 cfm (Energy Star listing)
- Filter
- Washable pre-filter, activated carbon and True HEPA, on both sides
- Replacement filter
- Max 2 filter set (fits the 400 and 400S), up to 1 year
- Noise (maker)
- 22–52 dB
- Power
- 66 W
- Warranty
- 5 years
Which rooms it suits
Everyday: AHAM's room size. Smog: AHAM's advice for smoke, a CADR at least equal to the floor area in ft².
| Room | Everyday | Smog days |
|---|---|---|
| Bedroom · 15 m² (161 ft²) | ||
| Living room · 30 m² (323 ft²) | ||
| Large room · 50 m² (538 ft²) |
Our take
The Airmega 400 draws air in through both sides, each with its own pre-filter, carbon and HEPA filter, which is how it reaches a smoke CADR of 376 cfm in its Energy Star listing. That suits an open-plan room of about 54 m².
A ring on top shows the air quality, and smart mode sets the fan from it. The 400S is the same machine with an app.
Coway's "1,560 ft²" assumes two air changes an hour. The AHAM-style room size is about 583 ft² (54 m²).
What's good
- 376 cfm, verified by Energy Star
- From 22 dB on low
- 5-year warranty
What's not
- Premium price
- The filter set is costly to replace
Its filter: Coway Airmega 400 Replacement Filter Set · $129.00 at cowaymega.com
Good for
- Open-plan living rooms up to about 54 m²
- One machine for the main room instead of two small ones
Skip it if
- You want app control: that's the 400S
How it compares
Every air purifier in the shop.
| Product | Best for | Smoke CADR | Room size | Price |
|---|---|---|---|---|
| Levoit Core 300S | Smart bedroom | 141 cfm | 20 m² | $149.99 |
| Levoit Core 300 | Budget bedroom | 143 cfm | 21 m² | $89.99 |
| Levoit Vital 100S | Pet-friendly bedroom | 143 cfm | 21 m² | $119.99 |
| Coway Airmega 150 | Small & quiet | 153 cfm | 22 m² | $189.99 |
| Levoit Core 400S | Shows PM2.5 | 231 cfm | 33 m² | $189.99 |
| Winix C545 | Everyday pick | 232 cfm | 33 m² | $209.99 |
| Coway Airmega AP-1512HH Mighty | Best overall | 233 cfm | 34 m² | $239.99 |
| Coway Airmega AP-1512HHS (Mighty with Wi-Fi) | Smart Mighty | 233 cfm | 34 m² | $299.99 |
| Coway Airmega 200M | Mighty's twin | 233 cfm | 34 m² | $229.99 |
| Levoit Vital 200S | Pet homes | 250 cfm | 36 m² | $169.99 |
| Honeywell HPA300 | No-frills power | 300 cfm | 43 m² | $269.95 |
| Coway Airmega 400 (this one) | Big rooms | 376 cfm | 54 m² | $649.00 |
| Levoit Core 600S | Large rooms | 391 cfm | 56 m² | $299.99 |
| Blueair Blue Pure 211i Max | Most clean air | 435 cfm | 63 m² | $349.99 |
| Filtrete MPR 1900 MERV 13 filters for a DIY box-fan purifier (4-pack) | Budget build | — | — | $87.99 |
Its filter, and related models
Coway Airmega 400 Max2 Filter SetAirmega 400 · $129.00
In our buying guides
Questions about the Airmega 400
- What size room does the Coway Airmega 400 cover?
- About 583 ft² (54 m²). That's AHAM's room size for its smoke CADR of 376 cfm: the floor area, with an 8 ft ceiling, whose air it cleans about every 12.5 minutes.
- Is the Coway Airmega 400 enough for smog?
- For smoke and heavy smog AHAM suggests a smoke CADR at least equal to the floor area in square feet. By that measure the Coway Airmega 400 keeps up with a room of about 376 ft² (35 m²). Keep the windows shut and run it on high while the AQI is bad.
- Airmega 400 or 400S?
- The same purifier; the 400S adds Wi-Fi and the IoCare app. If you're happy with the buttons and smart mode, the 400 does the same cleaning.
How we judge. We haven't tested the Airmega 400 in a lab of our own. The figures come from independent ratings (AHAM, Energy Star, NIOSH, the ASPCA) or the maker, and the verdict is ours, from those figures. No brand pays to be listed. Last checked Nov 7, 2026.
Coway Airmega 400
$649.00 list price