We think Apple may be onto something – it doesn’t matter if your product looks like a cheese grater, if it does what it does well, then looks absolutely don’t matter. And this is the case with the AIRMEGA 400S from Coway, a beast of an air purifier that eliminates microscopic airborne irritants while doing so with as little noise as possible. Let’s take a closer look at the AIRMEGA 400S to see whether it belongs in your home or apartment.

AIRMEGA 400S The Smarter App Enabled Air Purifier Review

Massive Coverage Area

First things first: maximum coverage area. The 400S’ humungous motor and fans can clear the air in rooms as large as 1,560 square feet. Basically, entire living rooms, multiple bedrooms, attics, and basements can all benefit from a single 400S at your disposal. Furthermore, it does so while maintaining higher-than-average CADR ratings – 350 CFM – for all three measures (smoke, pollen, and dust).

Dual Inlets and Top-Facing Outlet

A lot of the magnificent air-purifying performance of the 400S has to do with the dual inlets. On either side of the air purifier are two oversized inlets and fans that suck in a tremendous amount of contaminated air shooting out perfectly clean air vertically for even distribution across spacious areas. The dual-inlet and top-facing outlet design also allow you to place the 400S anywhere you like, not just in corners, with reduced risk of obstruction.

AIRMEGA 400S The Smarter App Enabled Air Purifier

3-Stage Filtration – Pre-Filter and Max2 Filter

If there are three filter stages, then how come we only mentioned two types of filters? Don’t worry, we know our math. The first line of defense, like in any air purifier, is a pre-filter that captures larger debris (hair, fur, dust) from making their way into the finer filters and clogging them up.

The next step is the Max2 Filter which is actually a combination of an activated carbon filter that traps odor molecules, and a True HEPA Filter that traps microscopic particles (as small as 0.3 microns in size) up to 99.97% of the time. The 400S does NOT have an ionizer – a plus or a minus to some people depending on how tolerant they are with introducing ozone into their homes.

AIRMEGA 400S Air Purifier Review

Accurate Filter Indicator

Like any filter, the filters in the air purifier don’t last forever, which is why we’re grateful that Coway has included an onboard filter indicator that alerts us when to change the filters. The pre-filter can be wiped clean and dried, but the activated carbon and HEPA filters require a bit of help.

HEPA filters generally last up to six months before needing to be replaced, but this depends on the quality of your indoor air. As soon as the 400S senses that the HEPA filter is too obstructed, the air purifier will shine a bright LED warning light.

AIRMEGA 400S Air Purifier

Fast-Response Air Quality Monitor

Perhaps the best feature that an air purifier can have is a smart air quality monitor. The 400S’ monitor alerts users of how contaminated the air is so you can adjust the fan to the proper speed setting.

But what makes it even better is that on Auto Mode, you won’t need to push buttons on the control panel – instead, the 400S’ air quality monitor will work in tandem with the device’s fan by automatically selecting the most appropriate fan speed to get rid of pesky particles in a timely fashion. Basically, all you need to do is purchase this air purifier, set it to Auto Mode, and be on your merry way!

App and Voice Control

You might find it odd that the air prufier doesn’t have a remote control. We absolutely did, until we realized that the way you can control the air purifier from a distance is by connecting it to either Amazon Echo or by sending commands through your phone. The Coway IoCare Mobile App gives you full-control over everything – timer, scheduler, fan speeds, cleaning modes – with a simple tap of your phone’s screen.


Practically Noiseless by Air Purifier Standards

The one thing that makes the 400S stand out above the other 1,500-plus-square-foot air purifiers is its almost absolute silence. On Sleep Mode, the 400S generates a gentle 22 decibels of noise that can lulls you to sleep. On its highest speed, it produces an audible but still quiet (by air purifier standards) 52 decibels of noise.

Inaccurate In-App Historical Chart

No air purifier is perfect, but at least the problem with the 400S is not in the device itself but rather the smartphone app. The real-time readings of indoor air quality according to the app are, more times than not, overstated.

Your phone will show a higher-than-real quality rating than the onboard sensor detects. The good news is that this in no ways affects how the appliance switches between cleaning speeds on Auto Mode.

Coway Related Articles

Single Reviews
Coway AP-1512HH Mighty Air Purifier Review
Coway AIRMEGA 400S Air Purifier Review
Comparison Article
Coway AP-1512H vs. Germ Guardian AC4825
Winix 5500-2 vs. Coway AP-1512HH
Coway Airmega 400S vs. Alen BreatheSmart 75i


What can we say except the Coway AIRMEGA 400S is one of the best air purifiers we’ve ever tested? That sounds like an exaggeration, but believe us: there’s hardly an air purifier that can stand up to the awesome cleaning performance, noise level, and convenience as the 400S. So to answer the initial question of whether the 400S belongs in your home or apartment: you’re darn right it does

AIRMEGA 400S The Smarter App Enabled Air Purifier Review

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