Coway

Airmega 300 (model 300)

Coway Airmega 300 (model 300)

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Overall

#53 in

Air Purifiers

according to Reddit Icon Reddit

Sentiment score86% positive
12
1
1

Top Pros

Top Cons

Last updated: Jun 18, 2026

Reddit Reviews

Reddit Iconsissasassafrastic
5 months ago

Yeah, your boyfriend is totally wrong. KNKA appears to be a junk rebadged brand. These are typically very cheap with poor build quality, short-lived replacement filter availability, and lousy customer service. The 2,325 sq. ft. coverage rating is highly misleading. This is likely at 1 Air Change per Hour (ACH) which is far too low. You want a minimum of 4.8 - 5 ACH for relatively normal particulate pollution levels. Biggest red flag: no Clean Air Delivery Rates (CADRs) listed. Coway is a high quality consumer-grade brand. The [Airmega 300](https://cowaymega.com/products/airmega-300?variant=34493568647327) has a 5 year warranty, is energy efficient, and relatively quiet. Top Smoke CADR is 285 CFM. This means the largest room size it can handle is 427 sq. ft. with an 8 ft. ceiling. You can use the discount code **COWAYMEGA10** on Coway's website for an additional 10% off, which brings the price down to $398.70. Unfortunately neither of these will combat the chemical odors from lawn care treatments. Odors are gases or vapors which require many pounds of sorbent media. Sorbent media are activated carbon, activated alumina, or synthetic zeolites. Neither the KNKA nor the Coway have very much activated carbon; they are designed to capture particulates (such as airborne mold spores). Heavyweight sorbent media purifiers are very expensive, very loud, and clean the air more slowly than particulates-focused purifiers. An entry-level unit from a brand like AllerAir would be at least $600. And depending on the exact gaseous "species" you're smelling, you may need chemically modified sorbents to enhance removal capacities.

7 months ago

No, Dyson is one of the worst! The HP09 has terrible Clean Air Delivery Rates (CADRs). They just know how to market effectively. As **Rule 4** and the AutoModerator comment repeats, it's helpful to know the ceiling height. I'll assume it's 2.4 meters. 60 m^(2) x 2.4 = 144 m^(3). For rooms measured in meters, CADR should be at least 3 times a room's volume (in m^(3)). So the minimum CADR should be 432 m^(3)/h. If you have [allergies, health conditions, high pollution, etc.](https://www.reddit.com/r/AirPurifiers/wiki/index/how_to_choose_an_air_purifier_for_particulates/#wiki_when_higher_than_normal_cadrs_may_be_needed), multiply the room's volume by 4-6. So CADRs of 576 - 864 m^(3)/h. Coway is a high quality brand that's relatively quiet. I don't know exactly where you are, so I don't know what's available to you. But the [Coway Airmega 400](https://www.amazon.co.uk/purifier-restaurant-certified-HyperCaptive-filtration/dp/B099S9Y285) would be a very good fit (Amazon UK website linked). If you can't find that, the Coway Airmega 300 might suffice... although you may want to supplement it with a smaller Coway model like the Coway Airmega Jet.

Reddit Iconmanatelier
9 months ago

coway. coway hands down. with two cockatiels i keep one thats supposed to cover 2500 sqft in a tiny bedroom because well…. it requires it, but we want a second one for the rest of the house. they do purifying and have charcoal filters for odors which has been great for cooking etc in the past

Reddit Iconandraconduh
14 days ago

I have two Coway Airmegas (300 and 400) and one Austin Air Bedroom Machine. They've all been running for 24 hours a day for over 5 years and have held up great. They are all easy to move around. The Coways are light and the Austin Air is heavier but has wheels. If you don't want to clean the outer filter at least monthly, don't get a Coway. If you can't deal with something that's pretty loud on the highest setting, don't get an Austin Air.

Reddit Iconbjyanghang945
10 months ago

I have a CR box with 6 PC fans. The throughput is just not enough to deal with the fire smoke.. ended up turning my actual purifier’s fan speed up. I have the Coway 300. Speed 3(200CFM) worst day 2 of them running.

Reddit IconButtBong9000
10 months ago

Hell yeah. I have two air purifiers running 24/7 in my 1bd apartment and it makes such a huge difference

10 months ago

Sure! I have the Coway AP-1512 in my living room and the Coway Airmega 300 in my bedroom. Big fan of the Coway products. If you keep an eye on marketplace or Craigslist you can get a good deal on them secondhand since so many people bought filters during the fires and end up selling them

Reddit IconErik0xff0000
7 months ago

I have two of those for bedrooms and the bigger airmega 300 for kitchen/dining/living area. They've been working great for me (I get impacted by wildfires and my neighbors fireplaces).

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