Coway Airmega 400 Review: Flair without the Wi-Fi hassle!
Airmega 400 Specification
Product | Airmega 400 |
Dimension | 14.8 x 22.8 x 14.8 in (37.6 x 57.9 x 37.6 cm) |
Weight | 24.7 lb (11.2 kg) |
Fanspeed | 3 |
Coverage (up to) | 1560 sq. ft. (145 m2) |
Airflow speed | |
Dust free (CADR) | 350 cfm (595 m3/h) |
Pollen free (CADR) | 350 cfm (595 m3/h) |
Smoke free (CADR) | 350 cfm (595 m3/h) |
Humidifying(H) speed | |
Filtration | 4-stage |
Pre-Filter - Lifespan - Replacement cost ($) | Pre-filter (2 pack) Permanent +- 25 |
HEPA filter - Lifespan - Replacement cost ($) | Max2 (Green True HEPA filter) 1 year |
Carbon filter - Lifespan - Replacement cost ($) | Max2 (Activated carbon filter) 1 year |
Ionizer/ Technologies | |
UV-light/ PCO | - |
Other filter | - |
All-in-one filter - Lifespan - Replacement cost ($) | Max2 Filter 1 year +- 129.99 |
Optional/ Addon | - |
Noise level | 22 - 52 dB |
Power usage level | 6 - 66 W |
Timer/ Scheduler | 1, 4, 8 hours |
Sensors | Pollution sensor, Light sensor |
Auto mode | |
Air qualityAQ indicator | |
Filter change indicator | |
More color options | |
Wi-Fi/ BTBluetooth | |
ENERGY STAR | |
Remote control | |
Child lock | |
Warranty | 5 years |
Email/ Phone support |
Key features
- 4-stage filtration
- 2 Washable permanent Pre-filter
- MAX2 filter (True HEPA filter + Activated Carbon filter)
- 3 speed setting (Low, Medium, High)
- Dual side air inlet
- Separate Pre-filter and HEPA filter indicator based on real-time usage
- Autonomous Smart mode - Auto, ECO and Sleep mode
- Front AQ display indicator (Good, Moderate, Unhealthy, Very Unhealthy)
- Adjustable pollution sensor's sensitivity (sensitive -1 bar, normal -2 bar, less sensitive - 3 bar)
- Built-in timer (1, 4, 8 hours)
- 5 years warranty
Pros
- 4-stage filtration with very wide purifying coverage.
- Dual pre-filter that traps large particles from both sides of the air inlet.
- Max2 filter (Green True HEPA + Activated Carbon) is great against smoke and micron size pollutants
- Auto mode with adjustable sensitivity for more accurate detection.
- Sleep mode that automatically adjusts the light and speed when there is no light source.
- Pre-filter and MAX2 filter lifespan indicator is based on real-time usage and environment.
- Clear and accurate air quality display indicator.
- 5 years Airmega official warranty.
Cons
- Cheaper than 400S model but still relatively expensive.
- Expensive filter replacement cost despite only one annual filter change (Max2 filter).
- No remote access (via app) as 400 have to do without Wi-Fi connectivity support.
- Lacks optional Ionizer feature even though not everyone would utilize it.
The starters
A mirror to 400S, you can barely tell Coway Airmega 400 apart from its series. The “smart” exterior seamlessly blends in the air intake, it looks futuristic even from a far point. At 14.8 x 22.8 x 14.8 in dimension and 24.7 lb weight, it is not super bulky considering the 4 legs stand comes as standard. Same build materials as the Wi-Fi version so every part is solidly fitted with no uneven gap for air bypass. Up front, you will find a bright, LED air quality indicator that will show real-time indoor air quality. When air quality is good, the ring will change to Blue color. Purple when air quality is moderate. Pink when air quality is unhealthy. Red when air quality is very unhealthy. Air inlet is located on both sides of the air purifier along with the handy gripping handle.

Big, round buttons with indicator light, the controls are spread across both sides of the top panel. On the left corner, you will find a Timer, Light, Pre Wash, and Max2 change button with a round light sensor. Timer button will cycle between 1, 4, 8 hours of pre-set setting. The light button will turn on or off the front air quality indicator light. Like 400S, both Pre Wash and Max2 Change button will show the pre-filter Lifetime cleaning cycle at 5 levels: 100%, 80%, 60%, 49%, 20%, and 0%. To reset the Pre Wash and Max2 bar, press and hold the respective button for 2-3 seconds. The light sensor works by detecting the warmth of the surrounding light. When everything is dark for 3 minutes, sleep mode will activate automatically. Moving to the right corner, there are only two functions. The big Power button and a swipeable Air speed/ mode. The power button will turn on the air purifier. Pressing and hold the power button again for 2-3 seconds will turn it off. The Air speed/ Sleep mode selection is slightly quirky to use. Either tap the curve bar on desired speed/ mode accordingly or swipe up or down for a similar result. Lastly, there is one hidden function that most people didn’t know it exists. The pollution sensor’s sensitivity can be adjusted by holding the Light button + Smart bar. Select one of the air speed from speed 1 = sensitive, speed 2 = normal, speed 3 = less sensitive.
Again, here is the recap of the air purifier spec sheet. Starting with the 4 stage filtration, 3 fan speed, timer, Smart mode (Auto/ Sleep/ Eco). Monitoring tools include 2 separate pre-filter/ HEPA filter indicator and AQ indicator. Finally, 30 days money back guarantee, and 5 years warranty comes standard.
Airflow, speed, and CADR
What’s inside count
Airmega 400 filtration consist of dual Pre-filter, True HEPA filter, and Carbon filter. How the 4-stage filtration works is pretty straightforward. When air are sucked through either side of the air inlet, the Pre-filter will block out as many large particles as possible. This gives the Green True HEPA more freedom space for capturing micron size particles (0.3 microns). The freed Green HEPA filter would then focus on allergens without being burden by dust and hair. On the other end, Activated Carbon filter would solely focus on smoke and gas pollutants. Filter size and quality are up there but do note that this would be the end of the filtration line. No Ionizer or UV-light in the whole purification process.Keep it down
At what cost
^ Replacement filters/ estimated cost
Airmega 400 VS the challengers

Airmega 400S
Identical in design, airflow delivery rate, CADR and purifying coverage. Airmega 400S comes with Wi-Fi support for remote access and Amazon Alexa support. Incidentally, 400S is also the most expensive unit in Airmega lineup.
Airmega 300
Cheapest Non-WiFi Airmega model but without the real-time pre-filter/ HEPA filter usage indicator. Airmega 300 weaker airflow purifying and CADR output are also expected.
Coway AP-1512HH Mighty
Don’t need the super wide coverage or limited airflow delivery rate, Coway Mighty "might" do the trick. At a fraction of the cost, you'll get decent filtration and airflow output that can cover large room size.