Coway Airmega 400S Smart Air Purifier Review

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Welcome to our review of the Coway Airmega 400S smart air purifier, where we’ll find out whether the purifier is worth buying or not. We’ll dive deep into the specifications of the purifier, how it works, what filters it uses, and whether it’s worth the asking price or not.

Coway is known for bringing quality when it comes to products that improve the quality of your living. And air purifiers are such devices. With the Airmega 400S, you will only get the top-level performance. If you’re a techie, then you’ll adore this purifier.

It’s a very modern device. As every new air purifier at the moment should be. This one has an app to go with it, allowing the users to connect to it and control it from their smartphone.

But what about the performance? Is the purifier worth the money?

That’s what you’ll learn here. Stay tuned for our in-depth review of the Coway Airmega 400S air purifier.

Overview of Coway Airmega 400S Air Purifier

Let’s start by taking a closer look at what the purifier has to offer.

To start with, let’s mention the purification process. For it, there is a Airmax Max2 filter, which combines a True HEPA filter and an activated carbon filter to bring you a supreme level of performance.

And before the filter, there’s also the pre-filter, which takes care of the larger particles and “prepares” the air for the main filter.

This Max2 filter is composed of two separate filters that work in unison. First, the True HEPA filter makes sure that the air quality coming out of the purifier is on a premium level.

It removes 99.97% of all airborne pollutants, including mold, pollen, dust, dust mites, pet dander, toxins, and other particles of 0.3 microns or larger.

And if you’re worried about smells and odors coming from the purifier, you don’t have to be. The activated carbon filter takes care of all the smells and odors, and also of the toxins and other potential harmful chemicals such as NH3 and CH3CHO.

And the performance is only boosted by some of the smart technological implementations that the purifier uses. First, it lets you connect the device straight to your smartphone, allowing you to control it straight from the comfort of your couch.

And there’s also a smart LED sensor which tells you about the pollution levels – when you need to open the purifier, and when the air is clean.

The smart implementations are supported by the many useful settings that the purifier has. Firstly, there are five fan modes: smart, sleep, low, medium and high.

You can imagine that at the lowest setting, the device is aimed towards silence; at the higher end, it’s designed to bring you the maximum performance it can.


Pros and Cons of Airmega 400S

Considering everything we’ve written so far, let’s take a look at some of the pros and cons to make your decision easier.


+ Great filtering performance with the Max2 filter.

+ Smart features with an app that comes with it, letting you control the purifier from your couch.

+ The LED sensor keeps track of the air quality and tells you how clean the air is.

+ Smart options for choosing the performance of the filter – 5 fan speeds, timer settings, and automatic adjustments according to the air quality.


The app is somewhat buggy and still needs some improvements.

Slightly more expensive.

What is the Coway Airmega 400S Air Purifier Good For?

You’ll find this purifier useful for improving the indoor air quality while also not having to do too much of maintenance on the long run. It’s an especially good device for allergy sufferers, asthmatics, smokers, pet owners, and those who are worried about the indoor air quality.

We know that air quality indoors matters just as much as the outdoor air quality. That’s why the Coway Airmega 400S is an excellent choice. It has the Max2 filter, which takes care of the most airborne pollutants, as well as foul odors and smells. Some chemical compounds are also removed from the air.

  • Dust, dust mites
  • Pet dander, pet smells
  • Mold
  • Pollen
  • Smoke, smoke smells
  • Toxins, harmful compound chemicals such as NH3 and CH3CHO
  • Foul odors, smells
  • Smaller particles that cause allergies, asthma attacks

And you can see that the purifier takes care of almost all of the airborne pollutants. The True HEPA filter is known for removing 99.97% of all airborne pollutants, including those who are 0.3 microns in size or larger. Anyone looking to improve their indoor air quality will enjoy this product.

And it’s especially a good device for those who are looking for a technologically advanced, smart device. Plus, it looks great, so it will fit straight in with your overall design.

Is the Coway Airmega 400S Good for Asthma?

Yes, the Coway Airmega 400S is a great purifier to have if you suffer from asthma. We know that even the smallest sense of airborne pollutants such as dust, mold, pet dander, can easily cause asthma.

And that’s made especially worse if you have a smoker in your home, or if there is plenty of pollution in the air. Pollen will creep into the home, especially during the spring. And those are all potential pollutants that will cause asthma attacks.

With asthma, prevention is key. If you can, you should prevent as many pollutants as you can from entering your home, which is how you can easily prevent asthma attacks. And the Coway Airmega 400S is a great purifier to do that.

While the purification device of the purifier is nothing special – it has the True HEPA filter with the activated carbon filter, you can consider it to be somewhere near the top end of all air purifiers.

And the best of all is that you can connect to it when you’re not even home – so when you’re outside, for example, your indoor air will be prepared for you when you come home.

How Often Do You Need to Change Filters on Coway Airmega 400S?

One of the disadvantages of True HEPA and activated carbon filters is that you’ll need to replace them often. How often mostly depends on how much you use the purifier, and how much pollution there is in your home.

A general guideline when it comes to replacing these filters is to replace them when the purifier tells you so. The Coway Airmega 400S has an indicator that will tell you when you should replace the filter.

A rough estimate is to replace these two filters every 6 months. However, this will depend on the usage and what the purifier has to do to clean the air. If the loads are higher, then you can expect to change the filters more often.

As for the pre-filter, you’ll only need to clean it or wash it every now and then to make sure it works to its maximum capacity. This filter is made to make the job of the main filter easier.

And while replacing the filters will present an additional cost, you will simply have to do it to keep your home clean and safe. On the long run, you’ll only need to do it a few times, and you should consider it when you see the performance start to dwindle a bit.

Is the Coway Airmega 400S Air Purifier Good for Large Rooms?

There are two models to choose from when it comes to this purifier: the 1560 sq. ft. one and the 1256 sq. ft. one.

Both are good for larger rooms. But if you’re especially concerned that the smaller purifier won’t be able to clean your room, you should purchase the larger version.

And the best thing about this air purifier is that it’s so small that it will fit almost anywhere. And that is an exceptional quality to have, especially if you consider just how much the air purifier can clean.

Is Coway Airmega 400S Worth the Money?

Now onto the big question: is this air purifier worth your money and consideration?

We would say yes, the air purifier is worth the money. However, there are some considerations you will have to make before you buy it. It’s not a black-and-white decision.

If you’re looking for a technologically-advanced purifier with an excellent filtration system, then you should certainly go for it. It’s also great for larger rooms, and it has a relatively modern design.

At the same time, also consider two things: the app still needs some improvements, and the price is a bit steep. However, the performance and the overall design justify the asking price, in our opinion.


The Coway Airmega 400S is the next in line when it comes to quality air purifiers coming from Coway.

If you’re looking for a great purifier that will do an excellent job at purifying, then this one is a great choice. And you’ll also get some amazing, tech-savvy options for those who want that.

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