Coway AIRMEGA 400S Air Purifier: Trusted Review & Specs

Coway latest flagship the AIRMEGA 400S is a vital device that will almost certainly shape the design of the iconic series going forward. Today, we will make a Coway AIRMEGA 400S Review to help Breathe Quality’s readers determine to invest into this device or not.

In Breathe Quality, we have reviewed all air purifiers under these sections. Also, we guarantee that:

  • We do give honest reviews (both pros and cons) so anyone will guarantee to have the wisest choices.
  • We do not (and never) exaggerate one product just to let you click the links and buy that product blindly.


airmega 400S review


  • Awesome technology from Coway
  • Stunning design
  • Large room coverage
  • Well-built than previous devices
  • Smart App Features

  • App receives many negative reviews
  • High cost filter replacement

There is one reason the Korean giant – Samsung is not successful at air purifier industry over the world, and it is this brand. With nearly 30 years in air purifier industry, Coway is a true symbol to life-care service sector in Korea. AIRMEGA is the result of years of extensive research and development that Coway put this name aside their traditional air purifiers, so they can improve and develop it better. Now, because you are here, let’s see if we should consider this AIRMEGA 400S at home.

Related post: Coway AP-1512HH Review.

AIRMEGA 400s Price

As good as the AIRMEGA 400S is though, it’s not perfect. It also comes at a cost that might make you to think it through.

Coway’s ambition to target high-range segment with this flagship. AIRMEGA 400S separate to 2 main editions, with different price tag on each of them. While the AIRMEGA 400S version is better with an automatic Sleep Mode and both Android and iOS app connection, it will cost you $100 more than the no-app AIRMEGA 400 model.

Both of these devices are available in two colors (one of Coway’s tradition to have 2 color editions), which are White and Graphite.

So, if you need the Smart Features on your air purifier, AIRMEGA 400S will cost you around $749 to $849 in official website. However you can look below for an incredible deal that can’t be missed.

Top AIRMEGA 400S deals right now

Coway AIRMEGA 400S Air Purifier with best air filtration technology in Graphite Edition. New products from $660.

The stylish Graphite edition for one of the best air purifiers in 2018. Deal for a limited time.

Related post: Best air purifiers list.

AIRMEGA 400S Design and Size

Coway has never been coasting for too long with any types of design. And that all changed since the AIRMEGA 300S, in a big way. AIRMEGA 400S closely resembles this design style, with a bigger form.

If you’ve seen the AIRMEGA 300S then the AIRMEGA 400S steps in as a dead ringer. Howerver, AIRMEGA 400S genuinely offers something different.

AIRMEGA 400S packs all the design tweaks and material choices that debuted with the AIRMEGA 300S: a bulky device with 22.8″ in height and with 4 legs. This air purifier feels thicker and more difficult to move from one place to another. Grabbing it one-handed has proved a hard feat for me, with a very narrow handle and a weight of 24.7 lbs. AIRMEGA 400S weighs as much as double the Coway AP-1512HH, and easily match the weight of Honeywell HPA300.

There are no major difference from both the front and the back of AIRMEGA 400S, with air grill from everywhere. This design concept is mostly because of the large room coverage of AIRMEGA 400S, to help you can put this air purifier anywhere to reach maximum efficiency. The only exception is the air quality indicator on the front to show the current air quality in your room.

On top of this air purifier is a typical air vent to take out the fresh air. Also, you will find the controller here. AIRMEGA 400S is a smart devices so it no longer has as many buttons as the previous Coway air purifiers. We will have only one on/off button and two air filter indicators.

airmega 400S review

Source: Amazon

Coway claims AIRMEGA 400S is the strongest ever. From both its look and the pretty well-built materials, we could expect a device that could last for a long time.

Related post: Best air purifiers for bedroom.

AIRMEGA 400S Filters

The unique feature on the AIRMEGA 400S is the filters. To test the performance of an air purifier, you need to know the power of its air filters and also how many filters it contains. Typically, to have a powerful air filtration, an air purifier need to stuff as many as possible air filters to it. As as consequence, it makes difficult to set up and take out the air filters to/from your air purifier. As an innovative device of the future, AIRMEGA 400S combine to an all-in-one filter for easier installation:

  1. Pre-filter – A powerful washable pre-filter is available to help you capture large objects of contaminants. Remember to dry the pre-filter in the shade before re-installing it.
  2. Max2 filter – A combination of both Activated Carbon Filter and True HEPA filter, this filter can both capture up to 99.97% of airborne particles 0.3 microns. It also reduces more than 99 percent of volatile organic compounds and reduces fumes such as NH3 and CH3CHO.

Of course, the biggest controversy with the ionic filter irritating asthma and respiratory issues pushes Coway to remove this function from their latest flagships. Both devices in the AIRMEGA series, 300S and 400S will have no ion at all.

For the Max2 filter, it is double the size of a normal Coway Anti-virus HEPA filter. However, double the size doesn’t mean double the performance rating. We have tested both AIRMEGA 400S and the Coway AP-1512HH and the performance ratings of both ones are nearly the same.

airmega 400S review

Source: Coway

We feel that the following words have been present in every Coway reviews we’ve ever written, but the performance of the True HEPA filter from Coway manufacturers is very good. However, the jump we’ve experienced from this generation just isn’t as noticeable as other air purifier brands. For a $99 to $129 filters, we will expect a better True HEPA filter, right?

Related post: Best air purifiers for allergies and asthma.

AIRMEGA 400S Room Coverage

There are more significant improvements in room coverage for AIRMEGA 400S, but again, for the sacrifice of other specs. In the manual, the AIRMEGA 400S states that it can cover up to 1560 square feet. But if you double the air changes per hour (ACH), this air purifier is only effective at exactly half, for a 780 sq ft.

The ACH of AIRMEGA 400s is 2X to 4X. For a mid high-range air purifiers, this ACH is on par with Rabbit Air MinusA2, but not as good as how Honeywell HPA600B can do.

The CADR of AIRMEGA 400S is not told in the manual. But through many tests, we recorded a reliable CADR of 340 Dust/ 350 Smoke/ 400 Pollen. For a large room air purifier like AIRMEGA 400S, this CADR specs is quite insufficient to the room coverage of 1560 sq ft.

Related post: Best large room air purifiers.

AIRMEGA 400S Sound

We can all agree that one of the most winning advantages of Coway air purifiers is the quiet operation. For Coway AP-1512HH, we had experienced no air purifier could go as low as this device. As the flagship of Coway brand, AIRMEGA 400S must strictly follow this perfect noise level.

Well, you won’t be disappointed.

The noise level of Coway AIRMEGA 400S ranges from 22 db to a maximum of 52 db. This air purifier is as quiet as the Ultra Quiet Rabbit Air MinusA2, despite of having higher fan power. That’s why we mostly find AIRMEGA 400S in the professional offices.

Related post: Best air purifiers for office.

AIRMEGA 400S Power Consumption

One of our most FAQ is “Do air purifier use a lot of energy?” The fact is you need to use air purifier for a long time to be efficient. Especially for a large room air purifier like AIRMEGA 400S, the power consumption is one important criteria to decide if you should buy it or not.

With 66W, the power consumption of AIRMEGA 400S is quite reasonable. We never expect such an air purifier designed for large room could use less energy than a light bulb, right? For a same performance rating, AIRMEGA 400S only consumes half of the Honeywell HPA300 could do. Also, thanks to the reliable Eco Mode, we would expect much less energy to be consumed by this air purifier.

Efficiently, it would cost you around $40 per year. For a much better performance, this power consumption is just equal with some popular air purifier from another Korean brand, like Winix WAC9500 or Winix 5500-2.

AIRMEGA 400S Additional Features

Additional features are handy for making a high-end air purifier with ease of use. As a high-range air purifier, there are a lot more in this AIRMEGA 400S than a $200 Coway AP-1512HH.

First, you will benefit from the most accurate Smart Sensor in the world. There’s so much to say about the Coway automatic features, and most of them are good reviews. Most importantly, the unique Eco Mode from Coway air purifiers will help reduce the power consumption to as low as possible.

But the most anticipated part for this flagship is the Smart App Enabled function. Using the Coway IOCare Mobile app, you will receive the real-time air quality notifications, also with a filter lifetime monitoring, and scheduler. However, this IOCare app has received mixed reviews, and mostly negative. It seems Coway doesn’t bring out the full potential of App control. We have the feeling that there is a weak dev team behind the app development work.

Without the app, AIRMEGA 400S is still a high-end device with stable features like intuitive air quality indicator or LED filter replacement indicator.

Related post: Best air purifiers for smoke.

AIRMEGA 400S Customer Service

Coway is a one of the top electronic brands in Korea, meaning they will especially emphasize the importance of Customer Service. With global subsidiaries and regional dealerships that serves over 60 countries, you should believe in the 3-year warranty for every product from Coway brand.

Top AIRMEGA 400S deals right now

Coway AIRMEGA 400S Air Purifier with best air filtration technology in Graphite Edition. New products from $660.

The stylish Graphite edition for one of the best air purifiers in 2018. Deal for a limited time.

Our verdict

In the writer’s opinion, the Coway AIRMEGA 300S offers a same performance rating with a much more reasonable price tag than the successor AIRMEGA 400S. Nevertheless, I doubt anyone will be unhappy with the great performance and features brought by the AIRMEGA 400S. The one slight disappointment with regards to the power is that within a large room coverage of 1560 sq ft, AIRMEGA 400S should make a better fan power with higher CADR and ACH.

  • Cleaning Power
  • Portability
  • Features
  • Power Consumption
  • Price



  • Awesome technology from Coway
  • Stunning design
  • Large room coverage
  • Well-built than previous devices
  • Smart App Features


  • App receives many negative reviews
  • High cost filter replacement