Coway Airmega 400S
$$$ Flagship$649.99
tldr; Large room workhorse. Handles wildfire smoke. Wait for sales (~$350). Side intake - won't fit in corners.
$649.99 on AmazonSentiment Breakdown
46%Positive
Positive
46%Neutral
48%Negative
6%Based on 521 Reddit opinions
Strengths & Weaknesses
Each axis shows what % of Reddit comments are positive about that topic. Higher = more praise.
Key Features
- [Coverage] Designed to clean spaces up to 3,120 sq. ft. in 60 minutes
- [HyperCaptive Filtration System] Combination of a pre-filter, active carbon filter, and HEPA Filter reduces 99.97% of 0.3 micron particles, including pollen and other allergens. It also reduces volatile organic compounds and odor
- [APP and Voice Control] IoCare mobile app includes indoor and outdoor air quality monitoring, filter notification, scheduling, and speed and smart mode control. Coway Airmega also works with Amazon Alexa and Dash Replenishment
- [Smart Mode] With its Smart Mode feature, the Airmega automatically adapts to its surroundings by adjusting fan speeds based on the room's air quality. That means your unit is energy efficient without compromising effectiveness
- [Eco Mdoe] When the air quality in the room remains purified for 30 minutes or more in Eco Mode, the fan will turn off to conserve energy, kicking on again when pollution is detected
- 🏠 Ideal for 700+ sq ft open layouts
- 🔥 Excels at wildfire smoke removal
- 💰 Wait for sales - often hits $350
Sentiment Over Time
Historical Price Data
Coway Airmega 400S
Coway Airmega 400S
All-time low: $358(2023-06)
What Redditors Actually Say
What Redditors Say
Best praise vs top criticism for Coway Airmega 400S
Best Praise
+6 pts“Coway purifiers are top notch. i have an AirMega 400 model in the room where we keep our cat litter boxes. it's built like a tank and after a year, it still showed the filters at maybe 75% remaining. i replaced them anyway, as i know the carbon pellets were spent without a doubt, and wanted to combat litter box smells... but the filters were still in fine shape. Coway filters are like $80, but i found a review / test of third-party filters that didn't have any appreciable difference for $30. they make a bunch of different sized purifiers for different room sizes, so see what suits your sit.”
r/AirQuality
ViewTop Criticism
+6 pts“This is infuriating. I bought the 400 thinking it would be the best option to keep the air clean for my baby and now I come to find out that I could possibly be doing more harm then good? Im trying really hard to remain calm right now.”
r/AirPurifiers
View13 more quotes available below
Related Products
Frequently Asked Questions
Is the Coway Airmega 400S worth buying?
Large room workhorse. Handles wildfire smoke. Wait for sales (~$350). Side intake - won't fit in corners.
What do Redditors love about the Coway Airmega 400S?
Redditors highlight: 🏠 Ideal for 700+ sq ft open layouts. 🔥 Excels at wildfire smoke removal. 💰 Wait for sales - often hits $350.
What are the downsides of the Coway Airmega 400S?
Some criticisms include: "This is infuriating.
I bought the 400 thinking it would be the best option to keep the air clean for my baby and now I come to find out that I could possibly be doing more harm then good?
Im trying..."
How accurate are these ratings?
Our sentiment analysis is approximately 80-85% accurate compared to manual review. Products with more mentions (Coway Airmega 400S has 521) tend to have more reliable scores.
521 Reddit opinions analyzed • Last updated 4/15/2026