Coway Airmega 300S Review: Smart air purifier + covers 1256 sq. ft. + works with Alexa!

Love everything about 300 model yet wish it can be controlled remotely, Coway Airmega 300S air purifier is your answer. With mirroring features between them,  majority user that used Airmega previously would appreciate the familiarity this purifying machine brings. In comparison with the airflow output, applicable area, noise level, and power usage, does the additional Wi-Fi connectivity justify the premium price tag? Let's go through the air cleaner spec and our detail review below.
± 749 p
     Annual filter ^    
± 100 p
Online price*
Latest Amazon price

Airmega 300S Specification

ProductAirmega 300S
13.6 x 21.2 x 13.6 in
(34.5 x 53.8 x 34.5 cm)
Weight21.4 lb (9.7 kg)
Coverage (up to)1256 sq. ft. (117 m2)
Dust free (CADR)260 cfm (442 m3/h)
Pollen free (CADR)260 cfm (442 m3/h)
Smoke free (CADR)260 cfm (442 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
+- 99.99
Optional/ Addon
Noise level22 - 52 dB
Power consumption6 - 57 W
Timer/ Scheduler1, 2, 4, 8 hours (App), Scheduler
SensorsPollution 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 300S key features

  • 4-stage filtration
  • Equipped with Wi-Fi support (IoCare app/ Amazon Alexa)
  • Permanent Pre-filter
  • MAX2 filter (True HEPA filter/ Activated Carbon filter)
  • 3 fanspeed (Low, Medium, High)
  • Dual side air inlet
  • Dual Pre-filter and HEPA filter indicator
  • Smart mode (Auto, ECO and Sleep mode)
  • Real-time air quality indicator (Good, Moderate, Unhealthy, Very Unhealthy)
  • Scheduler/ Timer via app (1, 2, 4, 8 hours)
  • 5 years warranty

Airmega 300S review

  • 4-stage filtration with wide purifying applicable area (at 2 air charges).
  • Utilize 2 Pre-filter on each side of the air purifier that traps dust, pet hair while enhancing HEPA filter and Carbon filter lifespan.
  • Highly-efficient allergen, smoke and odor filtration with the combined Green True HEPA and Activated Carbon Max2 filter.
  • Convenience and practical Smart mode (Auto mode/ Sleep mode).
  • Separate Pre-filter and MAX2 filter lifespan indicator.
  • Remotely access the air purifier scheduler, timer, and other functions via IoCare app.
  • Real-time air quality display indicator.
  • Adjustable sensor's sensitivity (sensitive, normal, less sensitive).
  • Reasonable Max2 filter replacement cost that only requires one yearly change.
  • Standard 5 years warranty.
  • Expensive based price that is close to the non-Wi-Fi 400 version.
  • Last checked, app is slightly less refine compared with competitors app.
  • Little learning curve on setting up Wi-Fi connectivity for first time user.
  • No built-in timer. Only accessible via Airmega app.
  • Lacks autonomous sleep mode and real-time HEPA and Activated Carbon filter change indicator available in 400/ 400S models.
  • No Ionizer within its filtration list.

The starters

Airmega 300S dimension
13.6 x 21.2 x 13.6 in
(34.5 x 53.8 x 34.5 cm)
Airmega 300S weight
21.4 lb (9.7 kg)

A modern and quality product from Coway, Airmega 300S its basically 300 version with added Wi-Fi integration for IoCare app and Amazon Alexa support. Sharing the same dimension as 300 at 13.6 x 21.2 x 13.6 in/ 21.4 lb weight, the build quality is second to none with no visible gap or ozone off-gasing. Front design is as clean as it gets with only prominent LED ring indicator that shows surrounding indoor air quality. The air quality indicator will lit in blue and green when indoor air is good, green and yellow when indoor air is moderate, yellow and pink when indoor air is unhealthy, lastly pink and red when indoor air is very unhealthy. Instead of just one back air inlet in typical air purifier design, the air purifier utilize dual air inlet that sucks air on both sides. Speaking of that, you will also find two built-in handles on each side of the air purifier for easy transporting.

Airmega 300S control

Unlike most air purifier that places its control panel at front, controls are located at the top black panel that is only accessible up close. Separated into two sections, On the left, you will find a Wi-Fi button, Light button, Pre Wash button and Max2 change button plus a round light sensor. Wi-Fi button enables connection to nearby Wi-Fi network. The Wi-Fi LED indicator will blink when there is no connection or undergoing pairing. Once the air purifier is connected to a Wi-Fi network, the LED light will stay constant. Next to it is the light button that activates/ deactivates air quality indicator light. The bottom two buttons (Pre Wash/ Max2) will lit once the filters require cleaning (Pre Wash) or change (Max 2). To reset the button indicator light, press and hold the buttons for 2-3 seconds. The small Light sensor is not a button; it detects the intensity of the surrounding light and activates Sleep mode if the condition stays more than 3 minutes. This function can be overwritten if the air purifier is not in Smart mode (manual speed) or high pollution level is detected. On the right, you have a big Power button, a small Air speed/ mode button, and five small indicator light to reflect on the current operating mode. Power button will obviously turn on/ off the air purifier (hold for 2-3 seconds), Air speed/ mode button will cycle between the 3 fan speed, Smart mode, and Sleep mode. The air purifier pollution sensor’s sensitivity can be adjusted too, but it requires a combination of 2 buttons. First, press and hold on to the light button, then press the Air speed/ mode button repeatedly until the desired sensitivity is selected. 1 fan bar = sensitive, 2 fan bar = normal, 3 fan bar = less sensitive. On the whole, there are plenty of dedicated button controls that is well-indicated for easy access.

Here is where the differences play it part. Coway Airmega 300S comes with Wi-Fi support which allows you to manage your air purifier via Airmega mobile IoCare App. Available in both iTunes and Google Play, pairing the air purifier is pretty straightforward for both iPhone and Android phones especially on higher end model once you are used to the standard procedure. Through IoCare app, you can remotely control your air purifier fan speed, switch to Smart/ Sleep mode, real-time air monitoring plus Indoor/ Outdoor Air Quality Report and scheduler/ timer. While timer comes with pre-set 1, 2, 4, 8 hours setting, scheduler is no doubt our favorite where you could program up to weekly schedule to turn on or off the air purifier. Also works with Amazon Alexa where you could link it via devices like Amazon Echo. Standard list of voice command includes activating/ deactivating the air purifier, switching to Smart/ Sleep mode, altering the fan speed, set timer, check filter life status and air quality.

To repeat, here are the standard features available in the air purifier. A 4 stage filtration, Smart mode (Auto/ Sleep/ Eco), 3 fan speed, Wi-Fi enabled (IoCare app/ Alexa) separate pre-filter/ HEPA filter indicator based on runtime, scheduler/ timer, air quality indicator, 30 days satisfaction money back guarantee, and 5 years manufacturer warranty.

Airflow, speed, and CADR

Airmega 300S coverage
Purifying coverage
1256 sq. ft. (117 m2)
Airmega 300S fanspeed
Comes in standard 3 speed + Smart and Sleep mode, Coway Airmega 300S has a toned down airflow performance and purifying coverage compare with its 400 series. At 1256 sq. ft. with 2 air charges every 30 minutes and 628 sq. ft. with 4 air charges every 15 minutes, there is still plenty of airflow punch even if you opt for the higher 4 air charges purifying speed. Pollution sensor functions accurately thanks to the adjustable sensitivity. Smart mode will automatically set the right speed based on surrounding air quality while Sleep mode would set a lower speed to reduce noise and power. Great for residential home at living hall, basement or even bedroom (with Sleep mode).
Airmega 300S dust CADR
260 cfm (442 m3/h)
Airmega 300S pollen CADR
Pollen CADR
260 cfm (442 m3/h)
Airmega 300S smoke CADR
Smoke CADR
260 cfm (442 m3/h)
Airmega 300S CADR is also equally impressive at a rounded high 260 cfm for dust, pollen, and smoke. There are no differences in airflow performance VS 300, but there is a clear gap between the 400 series. Nonetheless, anything above 200 cfm would be good enough for all types of indoor irritants including dust, microbes allergens, and smoke.

What’s inside count

Airmega 300S Pre-filter
Pre-filter (2 pack)
Airmega 300S HEPA filter
Max2 (Green True HEPA filter)
1 year
Airmega 300S carbon filter
Max2 (Activated carbon filter)
1 year
^ Airmega 300S filters/ technologies/ lifespan
The familiar 4-stage filtration setup found in every other Airmega models, Coway Airmega 300S works exactly like 300 with dual Pre-filter on both sides, a Green True HEPA filter and Activated Carbon filter in its core. Whenever the air purifier pulls air into the machine, the first-stage pre-filter on each side would block out large, airborne contaminants and leaving only small particles alone in the journey. With only microscopic allergens left, the Green True HEPA filter would unconditionally trap allergens and germs as small as 0.3 microns with an effective rate of 99.97%. For smoke, odor, and chemical gases, the Activated Carbon filter comes into play with an efficiency rate of 99%, before releasing purified air back out. Like any of the Airmega models, there is no ionizer or similar technology intact, so the air purifier solely relies on the quality of its Max2 filters.

Covered against

Airmega 300S VS Dust



Airmega 300S VS Pollen



Airmega 300S VS Hair

Hair/ Pet hair


Airmega 300S VS Dust mite

Dust mites


Airmega 300S VS Mold/ Mildew

Mold/ Mildew


Airmega 300S VS Pet dander

Pet dander


Airmega 300S VS Virus/ Germ

Virus/ Germ


Airmega 300S VS Tobacco smoke

Tobacco smoke


Airmega 300S VS Chemical



Airmega 300S VS VOCs



Airmega 300S VS Smoke/ Gas

Smoke/ Gas


Airmega 300S VS Odor



In general, the high dust 260 cfm output, and wide 1256 square feet coverage are excellent in removing dust, hair from all angles. The Max2 Green True HEPA filtration will eradicate dust mites, pet dander, pollen, mold, mildew, bacteria, and viruses. On dealing with fumes and gases, 300S Activated carbon filter is also effective against VOCs from paint, cooking smell, detergent ammonia, tobacco smokes, cigarette odors, and indoor radon.

Keep it down

Airmega 300S noise level
Noise level
22 - 52 dB
Airmega 300S power consumption
Power consumption
6 - 57 W
Coway Airmega 300S 22 - 52 dB noise level might not be the quietest air purifier around, it is still considerably silent especially at sleep/ low speed and only audible background noise at higher speed. You can still use the air purifier in a bedroom although it's a little bit overkill at this stage. Power consumption wise, 6 - 57 watts is not too shabby given the number of airflow output; expect slightly lower consumption rate if this Energy Star air purifier remains engaged in Auto/ Sleep mode. Autonomous will prevent the fan speed from going above unless the air quality is not at an ideal level. Also, there is Eco mode where the air cleaner will automatically stop the fan from spinning if the surrounding air quality is good for at least 10 minutes.

At what cost

Airmega 300S MRSP/ RSP
+- 749
Airmega 300S annual filter replacement cost
Annual Filter Cost
+- 100
^ Replacement filters/ estimated cost
Coway Airmega 300S air purifier is not your typical budget-friendly model with cut-down specification. In fact, it is the complete opposite thus is even pricier than its peer models. Is the Wi-Fi enabled feature worth the extra dollar for an identical specification to Airmega 300? Only you can decide. On to maintenance cost, the mandatory filter replacement is not the most expensive in its class. You just need to replace the filter set on a yearly basis. The Max2 replacement filter is packed with Green True HEPA filter and Activated Carbon filter that you can easily purchase online.
The good thing is you can get the air purifier at a significant discount/ special deal (including free shipping) at around 100 - 200 dollar off the retail price at Amazon Alternatively, you can buy Airmega 300S air purifier from its official website with easy payment, free shipping, and best stock availability for all models. Lastly, consider online retailers like Walmart, Bed, Bath and Beyond, Kohls or Allergybuyersclub. Amazon is our pick, but only for brand-new as one should never go for a pre-owned/ refurbished or used unit.

Airmega 300S VS the challengers

Airmega 300

Airmega 300

Drop the Wi-Fi connectivity and price will drop even further. As mentioned earlier, Coway Airmega 300 is the same air purifier as 300S but at around 100 dollar cheaper.
Airmega 400S

Airmega 400S

This is the highest range in Airmega series that also comes with Wi-Fi and Alexa support. You'll get a wider purifying coverage, higher CADR return, and additional color option (Graphite). Price is of course the highest, and that itself is undoubtedly the biggest obstacle.

Coway AP-1512HH Mighty

Why not consider Coway top-selling model "The Mighty". Sure the specification does not match the raw power, it is still respectable and more importantly, the much lower price is a lot easier to digest.
Rabbit Air MinusA2 SPA-780N

Rabbit Air MinusA2 SPA-780N

Cheaper to own and maintain, Rabbit Air MinusA2 SPA-780N is also Wi-Fi enabled and has the upper hand with a 6-stage filtration, Negative Ion Generator, and a mountable frame body. On the downside, an expected reduced purifying coverage and clean air delivery rate.

 Good to know

Airmega 300S VS 300

Let's get straight to the point. Airmega 300S is the higher range version of 300 with WiFi-enabled feature. This allows the air purifier to support few simple voice commands from Amazon Alexa and access the full features of Coway Airmega IoCare App where you can control the fan speed, switch to few different modes, real-time air quality monitoring, and advanced scheduling/ timing. On the other hand, the cheaper, none S 300 version is more accessible and come with 3 built-in pre-set timer that can be set via the top control panel.

Airmega 300S VS 400S

As the name implied, both 300S and 400S is WiFi-enabled therefore will support Airmega IoCare app. 300S is the lower range version with 304 square feet smaller purifying coverage, 90 cfm less dust, pollen, smoke CADR but is around $100 cheaper and $30 less maintenance cost. On the other end, the more expensive 400S has 1 extra color option (Black), real-time pre-filter/ HEPA lifespan indicator, better airflow performance and wider purifying coverage.

Final thoughts on Airmega 300S

Coway Airmega 300S is a great, reliable air purifier as with the 300 model. Around 65%4-5 stars reviewers in Amazon like the HEPA+Carbon filtration strength against airborne allergens, smoke, and odors. Some users also like the convenience features like air quality monitor, Auto mode, and of course the remote access and scheduler via IoCare app. On the opposite end, a rather high 26% of 1-2 stars reviewers is frustrated with the latest, Coway Airmega IoCare app that is either impossible to use or all in Korean language. A small group of users also commented on the ineffectiveness against household irritants particularly odors. While the majority of the users still give a big thumbs up on the air purifier, do look out for future iOS or Android app update to fix any of the above-mentioned issues.

Verdicts and ratings

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Airflow delivery
Particle Filtration
Smoke Filtration

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