Airmega 400S is rated at smoke CADR 328, with 1,560-square-foot guidance at two air changes per hour.
Coway’s current product page and the ENERGY STAR record corroborate the large-room identity and delivery-rate class.
Source-led product analysis
Product Assessment
Verdict
Choose the 400S when app control is genuinely useful in a large shared room; choose the ranked 400 when the same core filtration with simpler controls is enough.
Full review
The Airmega 400S is a genuine large-room machine, not a broad low-air-change marketing exercise. Coway publishes smoke CADR 328 and 1,560-square-foot guidance at two air changes per hour, plus a 22–52 dBA range. Two washable prefilters and two Max2 filter sets provide substantial particle and carbon surface area, while automatic modes keep lower-speed use civilized.
The S suffix mainly buys connectivity: remote air-quality checks, schedules, timers, and app control. Independent testing supports the purifier’s smoke performance and quietness, but owner channels are split on the app and sensor value. The larger practical question is duplication—the ranked Airmega 400 uses essentially the same cleaning platform and already fills the high-output Coway role.
Also considered in
What stands out
- Smoke CADR 328 and two-sided large-room airflow.
- Low-speed quietness with automatic sleep behavior.
- Remote monitoring and scheduling on a proven Coway platform.
Tradeoffs
- Near-duplicate cleaning hardware relative to the ranked 400.
- A large cabinet and two replacement filter sets.
- Mixed app, sensor, and support experiences in owner channels.
Who it is for
- Connected large living rooms.
- Scheduled smoke-day operation.
- Buyers who want high airflow at restrained lower-speed noise.
Who should skip it
- Small bedrooms.
- App-indifferent shoppers.
- Buyers minimizing filter bulk and maintenance.
Key Product Facts
The 22–52 dBA operating range, automatic modes, scheduling, and remote monitoring suit large living rooms that also need calm overnight use.
Current Coway documentation lists the sound range, smart modes, app controls, light behavior, and dual-filter maintenance.
Independent reviews find strong smoke clearing and restrained noise, but question whether the app premium adds enough over the non-connected 400.
Three independent product reviews agree on the large-room performance while treating connected controls and overall value as the main decision point.
- Coway Airmega 400S Review · TechGearLab
- Coway Airmega Review: 300, 400, 300S, and 400S · Consumer Analysis
- Coway Airmega 400S Review: Real-World Test Results · Air Purifiers Hub