Coway Airmega 400 Review In 2023: Flair without the Wi-Fi hassle!

A brand that defines modern purifier to the next level. Coway Airmega 400 is exceptional for long-haul purifying. It is the perfect choice for busy folks that use it every single day without the need to monitor. Here is what most users considering this over the basic NON-S version would think about. Should I get the basic 300 version or should I top up a little more for 400 series? Find out the answer and read more about the air purifier performance in our Airmega 400 review.
online price (US)**
±749.00 $$$$$$/ 7

(annual filter cost ±130)

** MRSP (Manufacturer's Suggested Retail Price)/ RSP (Retail selling price) is accurate at the time of posting.
^ Annual filter cost is calculated based on filter price and 12 hours of usage. Pricing could vary depending on air quality, usage frequency, and speed.
` The indicated online price guides as follows: $ = under $50, $$ = $50-100, $$$ = $101-200, $$$$ = 201-300, $$$$$ = $301-400, $$$$$$ = 401-500, $$$$$$$ = over $500.

Coway Airmega 400 Specification

ProductCoway Airmega 400
14.8 x 22.8 x 14.8 in
(37.6 x 57.9 x 37.6 cm)
Weight24.7 lb (11.2 kg)
Coverage (up to)1,560 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
- Lifespan
- Replacement cost ($)
Pre-filter (2 pack)
+- 25
HEPA filter
- Lifespan
- Replacement cost ($)
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 level22 - 52 dB
Power usage level6 - 66 W
Timer/ Scheduler1, 4, 8 hours
SensorsPollution sensor, Light sensor
Auto mode
Air qualityAQ indicator
Filter change indicator
More color options
Wi-Fi/ BTBluetooth
Remote control
Child lock
Warranty5 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

Design and Usability

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.

Coway Airmega 400 Control

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, Coverage, And CADR

Despite the lack of Wi-Fi function, Airmega 400 never skim on airflow performance. Expect the same airflow delivery and applicable area with the S variant. At a maximum of 1560 sq. ft. with 2 air charges or 780 sq. ft. with 4 air charges, the air purifier produces plentiful of airflow output. Adding an adjustable pollution sensor, Default Smart mode is there for autonomous purifying. Sleep mode will reduce noise and speed intended for night use. Speaking of night use, 400 can be used in bedroom or even living hall as it has the capacity for large room size. CADR is equally powerful as the airflow delivery rate. At an overall of 350 cfm, all three dust, pollen, smoke, pollen passes our minimum benchmark. Combining the versatile Max2 filtration, the air purifier outpaces most competitor models CADR.

Recommended Read

Filters And Performance

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 99.999% of micron size particles (0.01 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.

Noise And Energy Usage

Noise level starts at 22 dB at low speed, and end at 52 dB at max speed. No the quietest air purifier around but is perfectly usable even in a bedroom. Given the air cleaner is Energy Star rated, expect a reasonable power usage of 6 watts to a maximum of 66 watts. For better energy management, Smart mode aka Auto/ Sleep/ Eco mode is here. Auto mode will ensure the machine conserve energy by running in optimum speed. Eco mode will stop the fan from spinning when there is fresh air in a room for at least 10 minutes.
Noise TypeDecibels
Coway Airmega 40022 - 52 dB
Breathing10 dB
Rustling leaves20 dB
Whispering/ Quiet library30 dB
Light rainfall40-50 dB
Conversation50-60 dB
Vacuum cleaner/ Hair dryer/ Washing machine65-80 dB
City traffic80-90 dB

Pricing And Maintainence Cost

Coway Airmega 400 air purifier is the non-Wi-Fi version as oppose to the Wi-Fi ready 400S. As such, pricing will be cheaper but do not expect the margin to be huge given the spec is identical. What you can expect is the same pricing for both white or graphite color variant. Expensive the air purifier may be, it does have a slight advantage in the filter change section. The Max2 filter set (HEPA + carbon) is modestly priced and only needs one change annually. So, is 400 value for your money? Yes, but there are cheaper options that provide greater price per performance ratio.
The MRSP might not be as feasible as competitor's model, you can still find plenty of great deal online. Amazon is our favorite spot as you can get Airmega 400 with 100-200 dollars knock off plus free shipping. Coway's website offers good discount and easy payment scheme but without the convenience of Amazon. There are retailers like Best Buy, Kohls, and Walmart that carries the brand but none with the promotional edge as Amazon.

Final Thoughts On Coway Airmega 400

Compiling the result of 160+ (and counting) Amazon reviews. The first thing that impressed 85% of the 4-5 stars raters is the wide purifying. Most people also agree on the True HEPA and activated carbon filters effectiveness. Design and usability are also on most users agenda. A few also praises the air purifier modern approach with features like Smart mode. A mere 12% of the 1-2 stars raters thinks this air purifier is a waste of money. They would rather go for a cheaper alternative like Winix, Honeywell. Some users also complained about the plastic smell after unboxing. In our humble opinion, 85% positive ratings is a strong indication that the air purifier works. The 12% complains can be rectified with buyer's return policy if they are not happy with the result.


  • 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.


  • 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.
Coway Airmega 400 Review

Max Fernandez

A loving father and a dedicated reviewer for airfuji.com with more than 1000 air purifiers under his belt. Max Fernandez is also one of the million patients currently suffering from asthma. Feel free to nudge him if you have any questions.

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