is a reader-supported site. As an Amazon Associate we earn from qualifying purchases. Learn more.

Coway AIRMEGA 400S Air Purifier Review

AIRMEGA 400S is, without a doubt, a powerful beast; the 400S can cover 1560 square feet rooms. The good thing is that this air purifier has a fantastic performance rating as well as a fantastic fan power to keep the room covered with pure, fresh air. 

Coway AIRMEGA 400S Air PurifierCoway AIRMEGA 400S Air Purifier

The real treat in this AIRMEGA 400S is the Smart Sensor. You can easily monitor the room air quality in your apartment with a simple light ring on. A LED screen will display the current air quality in the room. When the air is good, it will turn positive, and when it is terrible, it will turn negative.

AIRMEGA 400S Features

q? encoding=UTF8&ASIN=B01C9RIAFS&Format= SL250 &ID=AsinImage&MarketPlace=US&ServiceVersion=20070822&WS=1&tag=airpurifi mp 20&language=en USCoway AIRMEGA 400S Air Purifier

Feature Info
Air Quality Monitoring Coway Airmega’s pollution sensor communicates indoor air quality in real-time. The brightly colored LED ring lets you know how clean or dirty your indoor air is every minute of the day.
Smart Technology With its Smart Mode feature, the Coway Airmega automatically adapts to its surroundings by adjusting fan speeds based on the room’s air quality.

View On Amazon

Such a fantastic air purifier has many features. Many of the features are highly advanced technology which you can hardly find at other air purifiers.

True HEPA Filter

The powerful TRUE HEPA filtration system guarantees the purity for the fresh air in the room. This system is capable of trapping 99.97% of airborne particles, including allergens, mold spores, bacteria as well as viruses. This is the highest level of cleaning a home can have.

The true HEPA filter is an excellent choice for an air purifier filtration system if you are looking for ways to remove allergens from the air. As already mentioned, pollen, dust, mold spores are significant allergens, and many people get allergic reactions if exposed to these particles for a prolonged period.

Carbon Activated Filter

This filter can remove gases, smoke, and even dangerous poisonous gases from the air. Gases are hazardous to your health and in high levels can be deadly. This system is perfect for places with lots of bad odor. Bad odor like pet pee, onions, smoke, and even sweat can be removed with an activated carbon filter. Thanks to this filter your home will smell fresh and whole air will appear like it just comes from a fresh mountain top.

Real Time Pollution Sensor

Advanced technology like that of air purifiers is quite rare. An average air purifier simply doesn’t have the sensor that detects even the slightest increase in the particles in the air. As a result, you will still experience fresh air no matter where you place the air purifier.

Once the air purifiers detect a high level of air pollution, it will turn the LED ring on the air purifier to red color. Red color means that the air quality in the room is very unhealthy. If the ring turns color to yellow, that means that the air is polluted and unhealthy and you should as soon as possible turn the air purifier either to automatic mode or turn the speed on. Green color indicates that the air quality is moderate and that you should keep an eye on the indicator if it moves to a good state or an unhealthy yellow state. The blue color is the color you want to see all the time on the air purifier, and that simply means that the air in the room is good and healthy.

Smart Auto Mode

AIRMEGA 400S uses sensors, so why not use that sensor to automatically adjust to the level of pollution by turning the air purifier to auto mode. On auto mode, the air purifier will monitor air, and as soon as the quality of the air drops, it will adjust the speed of filtration. With this model, you can save money on not running air purifier on maximum capacity when the air is good. 

Dual Suction

Coway Airmega 400S have powerful air intake from both sides. Then the magic of air filtration is done in the middle of the air purifier, and fresh, clean air free from particles and allergens is released on the top of the air purifier. With such suction model, you can place this air purifier near the wall where it won’t bother anyone, just make sure you don’t place it in the corner because then one suction side will not work correctly.

Filter Indicator

Max2 Filter is the name of the primary filter in the AIRMEGA 400S which is built from True HEPA filter and deodorization filter known as an activated carbon filter. The air purifier monitors Max2 filter, and as soon as the filter gets unusable, the air purifier will tell you to replace it. The pre filter is also included in the filtration system. You should periodically clean the pre filter with a vacuum cleaner or maybe even use water to clean it properly. If you do use water, then make sure that before placing the pre filter back in an air purifier is completely dry. The good news is that there is also an indicator that will tell you when you need to wash pre filter. This will save you lots of time by not washing the filter when it is not required.

Designed for Room

Make sure that visitors or young children don’t mistake this air purifier for a table and place some stuff on top of it because that will not be good for releasing the fresh air back into the room. The boxed shape on four legs can make people mistake this air purifier for table or small furniture. As long as they understand that this is actually air purifier, there is no problem, and such design just proves that this air purifier can fit any room.

IoCare Mobile App

For advanced usage and to lift the air purifier to a whole new level is IoCare application made by Coway for their air purifiers. For now, only 400S and 300S can use advanced options that this application offers but in the near future other models will be added. On the app, you can from any place on the earth monitor and manipulate the air purifier as long as you have access to the internet. 

For real science fiction usage, you can use Amazon Alexa to control the air purifier with your voice. Dash replenishment service is also available to the users that use IoCare application. We can say that AIRMEGA 400S is a smart air purifier.

Five Modes

On the lowest speed, the noise level is entirely silent, and you can sleep with AIRMEGA 400S turned on without a problem. In case you need to use other modes than sleep mode, you can choose that on the air purifier options panel. High speed is the highest achievable filtration rate, and on this high level air purifier is making 43dB. Smart mode mentioned above is a highly recommendable option to use. With this mode, you can save money but as well keep the room at the best air quality level.


The timer is adjustable, and you can choose between 1,2,4 and 8 hours of continuous filtration. This option is very good to use when you can forget that you have turned the air purifier on. Simply always use this option, and your air purifier will not work when it is not supposed to work.

Filter Replacement

Max2 filters need to be replaced every 12 months. The price for the combo filters of true HEPA and carbon filter is not small, and you should know that before you decide to buy this product. The maintenance cost on this air purifier is a bit higher than on other lower or mid-range air purifiers. But you should also keep in mind that this air purifier is capable of filtering extremely large rooms of 1560 square feet. In other words, this air purifier alone can be used as a filtration system for a whole apartment. 

q? encoding=UTF8&ASIN=B01C9RIAE4&Format= SL250 &ID=AsinImage&MarketPlace=US&ServiceVersion=20070822&WS=1&tag=airpurifi mp 20&language=en USAIRMEGA 400S Replacement Filter
Feature Info
MAX2 Filter Technology The Max2 filter – a combined activated carbon and a True HEPA filter—captures and reduces up to 99.97 percent of particles 0.3 microns in the air, including pollen, pollutants and other allergens.
Green True HEPA Filter Traps 99.97 percent of airborne particles up to 0.3 microns in size.

View On Amazon

Replacing filters is easy, and it should not present a significant problem for anyone. Airmega replacement filters are made of high quality material, and all you need to do is put them in the air purifier, and that’s about it. The pre filter is not replaceable, but in case it gets destroyed or broken by the constant washing, you can order that filter too. The pre filter is much more affordable than the Max2 combo filter.


  • Useful in Extremely Large Room
  • Smart Sensors
  • Auto Mode
  • Mobile Application
  • Interesting Design
  • Good for Allergies
  • Good For Asthma Patients
  • Powerful
  • Energy Star Efficiency


  • When an air purifier gets packed with so many fancy options and advanced technology, it is pretty normal that the price you need to pay for it is not small. Because of that that is the only disadvantage of this air purifier, it is not available to all people because of the budget wall.


AIRMEGA 400S is not affordable air purifier, but those who have the budget to buy it will enjoy the fresh air that this device release. It can cover a huge room, and by that, it can be used as the main filtration system for a whole home. When you put things down like that, then you can say that even though you are paying a higher price for this product you are getting back a lot. Many owners of AIRMEGA 400S will agree with me, and I hope they put a good word about this air purifier below in the comments section.

Check The Latest Price On Amazon

Subscribe To Our FREE Air Purifier First Newsletter

By entering your email address you agree to get a weekly email newsletter from Air Purifier First. We'll respect your privacy and unsubscribe at any time.

Leave a Reply