Coway - Airmega 400S
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Based on 1 year's data from Jan 28, 2026 How it works
Liked most:
136
16
"its night mode is whisper quiet"
"how quiet it is. ... it's remained silent at night after a couple of years."
"Silent"
59
1
"Its true HEPA filter grabs fur and dander"
"Best air filter we have ever owned. ... We have 4 of them in a 4000+ square for house where we foster cats (10+ at any time,) and the amount of fur, dust, and general particles it filters out is amazing. ... Friends who are severely allergic to cats come over with zero issues with these filters running."
"It wasn't until I upgraded to 2 winix machines that I finally got relief and it was instant."
23
2
"Last year there were wildfires nearby and the airmega kicked itself into high gear (I keep it on auto), so I do really trust that it’s actually doing something."
"The sensors are amazing. ... Yes whenever I cook or smoke they instantly kick on and work really well."
"the air monitoring report and air quality sensor. I've had a home improvement project going and as soon as dust started flying the air filter on auto setting cranked all the way to the max to counter."
36
4
"dealt with wildfire smoke perfectly."
"this thing has been amazing!!! ... I have two kids with seasonal allergies and this thing has been amazing!!!"
"The sensors are amazing. ... Yes whenever I cook or smoke they instantly kick on and work really well."
22
0
"I've had a Coway airmega going 24/7 for six years that hasn't developed any noise problems"
"They've run 24/7 for years without an issue."
"we’ve had a Coway Airmega running continuously 24/7 for the last 6 years"
Disliked most:
55
38
"the medify one sounds horrible- it has a weird high pitch and i can’t stand it even on the very lowest setting. ... i actually sent it back and they replaced it and the second one sounds the same."
"The only smaller air purifier I have is the $200 Conway in my kitchen. Its like a jet engine when on high speed. That's OK when I've burnt something. But there is no way people are running it at that noise level in general use."
"And it’s noisy as hell when I kick it up a notch."
7
2
"The off gassing on mine was terrible."
"tried the Conway and there was so much plastic offgassing. I returned it.."
"It's all cheap plastic construction"
10
12
"All of the conventional options recommended won’t cut it if you’re being serious. ... I have a few coway airmegas and blueairs and they don’t do much for real VOCs/smoke. ... My airmega has like 1lb of carbon, I’d recommend an allerair- I’ve got two airmedic 6 pro and the difference is remarkable. I think they have 25+ lbs of carbon."
"I bought it to reduce VOCs, however according to my sensor it loses effectiveness in under a month, then you are on the hook for a new $300 filter. ... A replacement filter lasted a similar amount of time for VOC effectiveness."
"So I purchased Austin Air Healthmate+ HM450 believing the higher carbon content in its filters will be more effective but after I tested it today it is also not making much of a difference. ... Austin Air HM450 has 15 lbs of activated carbon. Is that also not enough to make a dent? ... There’s no wildfire smoke currently. But my Voc is at around 225ppb. And no matter for how long I run the purifier, it stays at that level."
0
1
"after buying the Levoit I realised the sealing of a purifier's filter really is something that I didn't consider. As someone with allergies the last thing I want is for dust to slip through the side of the filter and be thrown back out at me."
34
32
"I literally just bought the Airmega 350 on Amazon and immediately regretted since I can't find the replacement filters for sale anywhere. ... Coway finally responded but wasn't helpful. They said they don't know when the filters for the 350 will be released."
"450 is round. New design. Not as good but more trendy. ... Higher claimed CADR. It is round so that number will go down rapidly. ... The VERY SHORT version, although ... there's a sticky ... is that round units are not inferior due to their shape. They're inferior because ALMOST WITHOUT EXCEPTION they have: * No removable pre-filter * Minimal Carbon, placed after the main filter * Deformable main filter * Smaller fans which have to spin faster to move more air therefore have a shorter lifespan * Shorter filter life leading to more costly replacement * Questionable filter efficiency, since it's difficult to manufacture a deformable HEPA filter. Levoit in particular claimed their filters were HEPA but they weren't at the time. They might be now, since they've started shipping them reinforced. * Instructions to VACUUM YOUR FILTERS, which pretty much means they're not HEPA. ... The airmega round units are, unfortunately, no exception."
"filter replacements can get pricey though ... filters are WAY overpriced considering you can get the machine with 2 filters for $120.."
Bostonianne 1.0I like Coway. Silent, dealt with wildfire smoke perfectly.
CalmSeaweed1360 1.0I’ve got two cats and a golden retriever, so air purifiers became non-negotiable for me. The one that’s made the biggest difference is the Coway Airmega 400S.
CaptainSwinky 1.0I’ve been drowning in dog and cat hair until I got a Coway Airmega 400S. Its true HEPA filter grabs fur and dander, and the activated carbon core neutralizes pet odors.
confused_megabyte 1.0Ugh. I just bought a 400S a week ago. Should I return and get the 400 instead? I do like that I can tell google to turn it on or off. But it’s almost a 200$ convenience.
They aren’t going to price match 400 price for 400S. The price of 400S hasn’t changed.
crusty-dave 1.0FYI: the fan on the microwave can still help, there is usually a carbon filter that will need periodic replacement. I just placed a Coway 400s next to my 3D printer. The carbon filter definitely helps when I am printing ABS filament. I also have some older 6 fan Shark towers that are now discontinued. They don’t have carbon filters, but still helped a great deal when cooking. For my Cuisinart electric grill, I have a smaller Shark cylinder next to it. When I grill salmon it quickly goes into low air quality (red) mode. The other units on the first floor (two Shark 6 fan towers) also go red and max filtration. Bottom line is that I find air filtration works well, but it does take some time to exchange enough air to reduce the cooking odors. Maybe a half hour with 2 large and one small unit running in auto mode. I think that two well placed Coways would probably exchange enough air to eliminate the odors fairly quickly. Put a smaller unit in the kitchen on the countertop near the stove for even more air exchange.
denishill 1.0Yeah Coway Airmega works so well. I have S400 and it's been fantastic.
District98 1.0Fit-Interview-3886 1.0I’ve got two cats and a dog, so air purifiers were kind of a must for me. I’ve tried a few, and the one that made the biggest difference was the Coway Airmega 400S. It’s pricey, but it actually cleared that faint pet smell that never goes away no matter how much you clean.
lalabearo 1.0second the airmega! I did a lot of research and my pediatrician recommended it as well (not that she’s an air quality expert, but I do trust her opinion on a lot of things!) I have a double coated dog and a cat and I really think it helps a lot. I will also say, we recently moved into a house with a lot of carpet so we bought a new Miele vacuum. My dad who has really bad pet allergies commented about how little he felt his allergies coming on the last time he was over.m
linkmodo 1.0I bought a used Coway Airmega 400S for $200, that came with a brand new set of OEM filters, the best purchase ever, and large enough to quickly cover 700 sq ft space in about 15 min for a complete air exchange. CADR (Clean Air Delivery Rate): 328 (Smoke), 328 (Dust), 400 (Pollen) Really love how quiet it is and the air monitoring report and air quality sensor. I've had a home improvement project going and as soon as dust started flying the air filter on auto setting cranked all the way to the max to counter. The over 350CFM air flow pushes a massive amount of air on max and surprisingly it's not even as loud as my old Holmes HAP756NU at medium setting.
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