Airmega 400S

Coway Airmega 400S Review: Whatever you need in this Smart enabled air purifier!

Dig Airmega looks and has all the money in the world? Coway Airmega 400S would be THE perfect choice.  Comes with all kinds of purifying functions plus Wi-Fi connectivity (IoCare app support), 400S would give you all the top rated features plus max airflow performance it can churn out. Similar to other air purifiers in terms of design and functionality, what other components would make this purifying machine stand out even more? Head over to our detail review below.
± 849 p
     Annual filter ^    
± 130 p
Online price*
Latest Amazon price

Airmega 400S Specification

ProductAirmega 400S
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)1560 sq. ft. (145 m2)
Dust free (CADR)350 cfm (595 m3/h)
Pollen free (CADR)350 cfm (595 m3/h)
Smoke free (CADR)350 cfm (595 m3/h)
Airflow 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 consumption6 - 66 W
Timer/ Scheduler1, 2, 4, 8 hours (App), Scheduler
SensorsPollution sensor, Light sensor
More color options
Auto mode
Air qualityAQ indicator
Filter change indicator
Wi-Fi/ BTBluetooth
Remote control
Child lock
Warranty5 years
Email/ Phone support

Product image

Airmega 400S key features

  • Wi-Fi connectivity for AIRMEGA app integration
  • Works with Amazon Alexa
  • 4-stage filtration
  • Permanent Pre-filter
  • MAX2 filter (True HEPA filter + Activated Carbon filter)
  • 3 fanspeed (Low, Medium, High)
  • Dual air suction via side air inlet
  • Dedicated Pre-filter and HEPA filter indicator (Change, Wash)
  • Smart mode - Auto, ECO and Sleep mode
  • Real-time air quality monitor (Good, Moderate, Unhealthy, Very Unhealthy)
  • Adjustable pollution sensor's sensitivity (sensitive, normal, less sensitive)
  • Scheduler/ Timer via IoCare app (1, 2, 4, 8 hours)
  • 5 years warranty

Airmega 400S review

  • 4-stage filtration with widest purifying coverage in its group.
  • Dual pre-filter that cover and protect the HEPA filter from large particles flowing through both sides of the air inlet.
  • Outstanding allergens and smoke filtration via its MAX2 (Full-size HEPA filter + Carbon filter).
  • Auto mode that accurately and automatically adjusts the fan speed based on room air quality.
  • Light/ sleep mode that automatically tones down the fan speed when the room is dark.
  • Separate Pre-filter and MAX2 filter lifespan indicator that calculates filter life based on real-time usage/ environment.
  • Timer + advanced scheduler for 7 days customizable on and off setting (via IoCare app).
  • Highly legible and accurate real-time air quality monitor.
  • Standard 5 years manufacturer warranty.
  • All Airmega air purifiers are expensive. This is the most expensive version of its series.
  • Filter replacement cost is high although Max2 set consists of both HEPA and Carbon filter.
  • At the point of this review, IoCare App is less refined and intuitive compared with competitors app.
  • Slight learning curve on Wi-Fi connectivity especially for first time user.
  • No Ionizer as an option.
  • Timer is only accessible via Airmega app.

The starters

Airmega 400S dimension
14.8 x 22.8 x 14.8 in
(37.6 x 57.9 x 37.6 cm)
Airmega 400S weight
24.7 lb (11.2 kg)

Simplicity meets modern architecture. Coway Airmega 400S manage to perfect the art of design VS practicality with its seamless dual side air inlet. Sharing the same dimension as 400, the 14.8 x 22.8 x 14.8 in size and 24.7 lb weight is considerably compact for its category if you discounted the four fixed legs. Build quality is top-notch that does not seem to be any signs of ozone off-gassing or air by-pass. Upfront the air cleaner comes with standard LED ring air quality indicator that shows real-time (every minute) indoor air pollution. Up to four different colors will be shown to indicate the current air quality status ranging from Good (Blue and green), Moderate (Green and yellow), Unhealthy (Yellow and pink) to Very Unhealthy (Pink and red). Finally, to lift or transport the air purifier around, simply hold on to both sides of the handles.

Coway Airmega 400S control

Airmega 400S controls are located at the top black panel that separates into two sections. On the left side, you will find a Wi-Fi button, Light button, Pre Wash button and Max2 change button plus a round light sensor. Touching the Wi-Fi button connect the air purifier to a Wi-Fi network. The Wi-Fi LED indicator will start blinking when the pairing is in progress and stays constant once a stable connection is established. The light button will either turn on or off the air quality indicator light. Pre Wash button will shows the pre-filter cleaning cycle at 5 levels: 100%, 80%, 60%, 49%, 20%, and 0%. Once the button is lit, you will need to clean the pre-filter. To reset the Pre Wash filter Lifetime notifications, touch and hold the button for 2-3 seconds until the button light is off. The above steps apply to Max2 Change button, but instead of cleaning the filter, you will need to replace the Max2 filter. Light sensor function by detecting the intensity of its surrounding light. When the air purifier is in Smart mode and everything is in pitch black for 3 minutes, Sleep mode will be activated automatically. Moving to the right side, you have a big main Power button that is self-explanatory. Touch the button once to turn on the air purifier, touch and hold the same button again for 2-3 seconds will turn it off. To manage the fan speed or purifying mode, either touch the air speed or Sleep mode on the curve bar, or swipe your finger upward or downward to select the desired speed/ mode. One more secret function that most people didn’t know unless they read the manual (how many of you does that), you can adjust the pollution sensor’s sensitivity by holding on the Light button +Smart bar. Continue by selecting one of the air speed ( speed 1 = sensitive, speed 2 = normal, speed 3 = less sensitive). Overall, all buttons are responsive, clearly labeled with dedicated indicator light, and an unseen, intuitive swiping speed control.

Like 300S, the Wi-Fi enabled feature that allows you to control the air purifier at any place via Coway IoCare app. Pairing is easy for both Apple and most Android phones so long you have strong Wi-Fi connectivity. We did encounter some issues with some lower end model (Huawei to be exact but that is few off case scenario) that requires multiple retries. Once successfully connected the air purifier to Wi-Fi network, you can access to features such as Smart Monitoring, Real-time Air Monitoring, Indoor Air Quality Report (including records from past week), Outdoor Air Quality Monitoring (check air quality in your city), Scheduler/ Timer, Speed and Smart Mode Control (Auto/ Sleep mode). Other than popular timer/ speed control, the highlights would definitely be the scheduler that allows you to program a weekly schedule when to turn on or off the machine. Airmega 400S also works with Amazon Alexa where you could manage the air purifier via the given list of command. The standard list of voice command includes turning on or off, switching to Smart or Sleep mode, changing the fan speed, set timer, filter life status and check air quality.

Briefly go through other key specification again: A standard 4-stage filtration, 3 fan speed with Smart mode (Auto/ Sleep/ Eco), Pre-filter/ MAX2 life-time indicator (actual filter real-time usage lifespan), Wi-Fi enabled for Airmega’s IoCare app and Amazon Alexa support (more on this later), timer/ scheduler (via app), air quality indicator, 30 days money back guarantee and 5 years warranty.

Airflow, speed, and CADR

Airmega 400S coverage
Purifying coverage
1560 sq. ft. (145 m2)
Airmega 400S fanspeed
Coway Airmega 400S is the top end in the series so naturally it has best in-class purifying coverage. With 2 air charges every 30 minutes, expect a wide 1560 sq. ft. purifying coverage. Coverage drop to half at around 780 sq. ft. coverage with 4 air charges every 15 minutes. For normal non-allergic situation, the 2 charges purifying coverage and airflow delivery rate is more than sufficient for most room size including living hall. Smart mode is the default mode that allows autonomous purifying according to room air quality. Switching to Sleep mode will reduce noise and power usage for night use, or manually select one of the 3 speed.
Airmega 400S dust CADR
350 cfm (595 m3/h)
Airmega 400S pollen CADR
Pollen CADR
350 cfm (595 m3/h)
Airmega 400S smoke CADR
Smoke CADR
350 cfm (595 m3/h)
CADR is also equally impressive as the purifying coverage. Overall dust, pollen, and smoke have an outstanding 350 cfm figures (Optimal speed). Significantly higher than most air purifiers CADR output within its segment. Based on the figures itself, the air purifier would have no problem handling heap of dust, indoor habitant microorganisms plus smoke and odor pollutants.

What’s inside count

Airmega 400S Pre-filter
Pre-filter (2 pack)
Airmega 400S HEPA filter
Max2 (Green True HEPA filter)
1 year
Airmega 400S carbon filter
Max2 (Activated carbon filter)
1 year
^ Airmega 400S filters/ technologies/ lifespan
Airmega 400S uses the same 4-stage filtration setup that is proven against the test of time. Essentially a dual pre-filter plus Max2 filter bundled (Green True HEPA filter and Activated Carbon filter), each pre-filter would be placed at both sides of air inlet to clear out any large incoming airborne contaminants before reaching to the Max2 filters. With large particles out of the way, Green True HEPA filter and Activated Carbon filter in Max2 would have the full capacity (99.7% for HEPA and 99% for carbon) in capturing tiny microorganisms, gases and odors. There is no optional Ionizer included in the filtration list; Not a big miss for some.

Covered against

Airmega 400S VS Dust



Airmega 400S VS Pollen



Airmega 400S VS Hair

Hair/ Pet hair


Airmega 400S VS Dust mite

Dust mites


Airmega 400S VS Mold/ Mildew

Mold/ Mildew


Airmega 400S VS Pet dander

Pet dander


Airmega 400S VS Virus/ Germ

Virus/ Germ


Airmega 400S VS Tobacco smoke

Tobacco smoke


Airmega 400S VS Chemical



Airmega 400S VS VOCs



Airmega 400S VS Smoke/ Gas

Smoke/ Gas


Airmega 400S VS Odor



Without a doubt, the 4-stage filtration and high 350 cfm CADR is effective against your typical airborne dust and hair. The extensive 1560 square feet coverage plus Max2 Green True HEPA filter is amazing in eliminating dust mites, pollen, mold, spores, mildew, bacteria, and pet dander. Max2 activated carbon filter would handle your cooking smoke, cigarette odors, smelly pet, VOCs and other household product chemicals off-gas.

Keep it down

Airmega 400S noise level
Noise level
22 - 52 dB
Airmega 400S power consumption
Power consumption
6 - 66 W
22 - 52 dB noise level is the same as 400 model. Reasonable but not overly silent at low speed and slightly lower to normal conversion noise level at max speed. Usable in bedroom if you crank it in Sleep mode. The 6 - 66 watts power consumption is in an identical pattern with low consumption rate at sleep/ low speed and high consumption rate at medium/ high speed. To further enhance the eco-friendliness, there is ECO mode where the air cleaner would shut down the fan when the room air quality is good for at least 10 minutes. Auto mode would also prevent any energy wastage where the air purifier would only run at a higher speed if the surrounding air quality is poor.

At what cost

Airmega 400S MRSP/ RSP
+- 849
Airmega 400S annual filter replacement cost
Annual Filter Cost
+- 130
^ Replacement filters/ estimated cost
Coway Airmega 400S air purifier is the highest in the brand hierarchy hence it is the costliest. We do think it's worth every penny you paid however, if you have no use of the supportive features, large room space purifying or the strong airflow delivery rate, maybe it's time to consider the smaller alternatives like Airmega 300S or other equivalent models. Annual filter replacement cost is more reasonably priced with plenty of availability, but do take note it is in a bundled Max2 set which consists of both HEPA and Activated Carbon filter.
Unlike some air purifiers that offer a fixed price across all retailers, Coway Airmega 400S can be purchased at around 100-200 dollars lower than its RSP price depending on the condition of the unit. We recommend Amazon as it has the highest discount percentage, 30 days no question asked return policy, and free shipping (prime). Coway official channel is not a bad place either with promotional price, free shipping (U.S. only), 30-day money-back guarantee and easy payment. Certain physical stores like Walmart, Kohls or Bed, Bath and Beyond might carry Airmega models that you can try your luck.

Airmega 400S VS the challengers

Airmega 400

Airmega 400

Identical in every way except it's around $100 cheaper due to the lack of Wi-Fi + Alexa support. Airmega 400 is the air purifier to go for if you have no use of the remote access.

Airmega 300S

The smaller, cheaper, and Wi-Fi ready version that is almost indistinguishable at first glance, Airmega 300S has a weaker overall performance and lacks filter real-time usage indicator.

Coway AP-1512HH Mighty

Coway best-selling air purifier that is priced a lot less yet with decent airflow circulation, Coway Mighty filtration performance is nevertheless incomparable to Airmega 400S.
Rabbit Air MinusA2 SPA-780N

Rabbit Air MinusA2 SPA-780N

Gain a brilliant 6-stage filtration, ionizer, and a body that is mountable to wall, Rabbit Air MinusA2 SPA-780N purifying coverage and airflow delivery rate is no match for Airmega 400 output.

 Good to know

Airmega 400S VS 400

400 is the cheaper version to 400S with identical purifying coverage, airflow delivery rate, and CADR. Features wise, it has a built-in timer on the control panel to replace the lack of Wi-Fi support. Airmega 400S Smart air purifier is exactly as the "S" variant implies, a higher spec version with added Wi-fi enabled features. You can remotely access 400S features via ioCare app or using Amazon Alexa voice command.

Final thoughts on Airmega 400S

Overall, we are satisfied with Coway Airmega 400S practicality in conjunction with the airflow delivery rate. Make no mistake though, this is an expensive air purifier which explains the low numbers (+- 179) of Amazon reviews online. Out of the bunch, 65% of the users gave it a 4-5 stars agree on the HEPA filtration efficiency against airborne particles, smoke, and odors. They also like how easy the air purifier works with air quality monitor, Auto mode, and Sleep mode that activates autonomously. A few also compliment IoCare app advanced scheduling feature. As for the negatives 1-2 stars, a high 26% of users dislike the following things about this air cleaner: 1. Smart mode aka Auto/ Sleep/ Eco that does not react quick enough to the air purifier surroundings. 2. IoCare app is virtually unusable since switched to Coway platform. 3. The air purifier is merely ineffective against allergens, smoke or odors. Clearly the pros outweigh the cons, ioCare usability is something you might need to look into, but we have confidence the app issue will be resolved in the coming months.

Verdicts and ratings

Build quality
Airflow delivery
Particle Filtration
Smoke Filtration
Airmega 400S

Frequently Asked Questions FAQ


Safety Tips

More on Airmega 400S review