The Airmega 400 is worth considering if you want physical controls, automatic operation and no app to manage. Before buying, check two things: the air-change rate behind the room-size claim, and whether a $129 replacement-filter set fits your budget. A large coverage number alone does not tell you how quickly a purifier will work in your room.
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What you get—and what you give up
Coway lists smoke/dust/pollen CADR at 328 / 328 / 400 CFM, noise at 22–52 dB(A), and power consumption at 66 W. The 400 has auto, eco and sleep modes, but no Wi-Fi or app. Its footprint is 14.8 inches square and its height is 22.8 inches. These are manufacturer specifications, not measurements from our own room.
The tradeoff is straightforward: choose it if you prefer controls on the machine; look elsewhere if remote scheduling from your phone is a requirement. Measure the intended location before ordering, especially if a square appliance would obstruct a walkway.
How much room can it handle?
Coway advertises 3,120 sq ft at one air change per hour and 1,560 sq ft at two. Those are different operating targets, not interchangeable definitions of a large room. A purifier making one pass per hour is not providing the same rate of cleaning as one making several passes.
For a separate sizing illustration, the table below uses the published smoke CADR, an 8-foot ceiling and the calculation 328 × 60 ÷ room volume. It estimates equivalent clean-air changes under those assumptions; it is not a certification, a pollution-removal time or a promise for sleep mode.
| Room area | Calculated clean-air changes/hour | Buying implication |
|---|---|---|
| 400 sq ft | 6.15 | More capacity per cubic foot than the larger examples |
| 600 sq ft | 4.10 | Check the fan setting you can tolerate |
| 800 sq ft | 3.08 | Less capacity per cubic foot |
Higher ceilings increase room volume. Lower fan settings can reduce airflow. Do not stretch the largest advertised area into a guarantee for several closed rooms. If smoke is your main concern, compare the sizing conditions in our wildfire-smoke purifier comparison.
Budget for a complete filter set
The genuine 400/400S Max2 set contains two filters, one for each side. Coway listed the set at $129 on September 22, 2026, with a 12-month life expectancy. The purifier page also mentions 6–12 months. Actual replacement needs depend on use; neither interval guarantees a fixed annual bill.
| Replacement assumption | Annual filter budget |
|---|---|
| One $129 set per year | $129 |
| Two $129 sets per year | $258 |
These are planning scenarios at the dated manufacturer price, excluding tax and any shipping. They are not Amazon prices or a prediction of your replacement schedule. For a used unit, confirm the model and Coway’s serial-code compatibility guidance before purchasing filters.
Coway recommends checking the pre-filters for cleaning typically every 2–4 weeks, depending on use. Turn off and unplug the unit first, and let washed pre-filters dry fully before reinstalling. Follow the model-specific maintenance instructions; cleaning a pre-filter does not remove the need to replace Max2 filters.
Electricity: calculate it with your own rate
At a constant assumed 66 W for 24 hours a day, the arithmetic is 0.066 × 24 × 365 = 578.16 kWh per year. At an illustrative $0.15/kWh, that would be $86.72 per year. This is a constant-power scenario, not measured annual consumption. Use your utility rate and realistic operating hours; auto and lower-speed use will not necessarily match that assumption.
Should you buy it?
Shortlist the 400 if its room-size calculation suits your space, you prefer an appliance without app setup, and replacement sets fit your ongoing budget. Skip it if your decision depends on a guaranteed low-speed cleaning rate for a very large space: the published figures above do not establish that. For another model decision, see our Mighty2 versus AP-1512HH comparison.
Check the Coway Airmega 400 White (AP-2015F) on Amazon
Questions before checkout
Does the Airmega 400 need an app?
No. This model has no app connectivity. Verify that the listing is the 400 rather than assuming similarly named models have identical features.
Is $129 the cost of one filter?
The official listing checked for this article prices a set containing both Max2 filters at $129. Check the current price and package contents before ordering.
Will it be silent while delivering the listed CADR?
The published noise range does not establish that the quietest setting delivers the listed CADR. Choose your room-size margin with the fan setting you intend to use in mind.