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The Airmega 230.

What Size Air Purifier Do I Need?

By the time you land on our site, you’ve likely already made an important decision–to make clean air a fundamental part of your lifestyle. 

That might sound obvious, but many of us don’t even give much thought to the air we breathe until we’re confronted by a wildfire, heavy pollen season, or air quality alerts in our region. By then, the damage could already be done. 

Once you recognize that you need an air purifier, the next step is to determine which size and model is best for your family and lifestyle. All of us want the most energy-efficient match for the area coverage required. So if you’re currently asking yourself “What size air purifier do I need?” it’s time to break down some technical concepts, such as Clean Air Delivery Rate and Cubic Feet Per Minute. 

What Is Clean Air Delivery Rate?

You wouldn’t buy a new car without checking the fuel consumption in miles per gallon, or a new washing machine or dishwasher without looking up the Energy Star rating.  

Likewise, we wouldn’t want you to buy any air purifier without a transparent guideline of what performance to expect. Luckily, we have some help from Energy Star, which uses Clean Air Delivery Rate testing data as the basis of its certification.  

Clean Air Delivery Rate (CADR) is the metric to measure air purification and filtration performance. To test CADR, an air purifier is isolated in a room and exposed to three kinds of environmental pollution:

  • Smoke
  • Dust
  • Pollen

The test measures how many Cubic Feet Per Minute of that pollutant the air purifier can remove. 

The higher the number, the faster the rate of filtration. 

There is a (quite complex) formula for calculating CADR, but realistically, you wouldn’t ever need to work it out. 

Here’s What You Need to Know About CADR

The only numbers you really need to pay attention to are:

  1. The CADR as listed by the manufacturer or recorded on the Aham Verifide directory. 
  2. For example, you’ll see in the product description that the Airmega 400 has a CADR of 285 (smoke), 358 (dust) and 450 (pollen). 
  3. This number multiplied by 1.55. 

That’s because, according to the AHAM “two-thirds rule”, the CADR of an air purifier or filter should be at least two-thirds the surface area of the room it is covering. 

So if your air purifier is listed by the manufacturer as having a CADR of 300:

Calculate 300 x 1.55 = 465. 

Therefore your device will work efficiently in a room of up to 465 square feet. 

A space with a large air purifier, the Airmega ProX.

A Warning About CADR

It’s worth noting that CADR is designed to measure the performance of an air purifier working at full speed within a small (around 1,008 square feet) chamber. 

The test measures how fast particles are removed, so it is not a useful reference for:

  • Filtration quality
  • Performance in Eco-mode or on auto setting
  • Effectiveness in redistributing clean air to all parts of the room

As a result, it’s best to use CADR as a way of comparing similar models/brands, but not necessarily as a way of evaluating ultimate performance. 

How to Choose the Size of Your Air Purifier

At Cowaymega, we’ve done all the math for you and have conducted our own rigorous testing to prove how efficient our air purifiers are in removing the particles other models can’t catch. 

We’re proud of the fact that our patented HyperCaptive Airmega filtration system removes 99.999% of particles from the air (down to 0.01 ㎛). 

It can help to filter your search by identifying the size of space you are looking to cover. This will then show you the most appropriate models for that category. 

  • Finally, you have the Airmega 160, 150, 100 and Airmega Aim for small spaces where purification of up to 1,035 ft2 per 60 minutes is required. 

The Importance of Filtration Quality

To go back to the car or washing machine analogies, you wouldn’t be happy with a car that had great fuel efficiency but belched blue smoke from the exhaust, or a washing machine that didn’t get your clothes clean (however energy efficient). Similarly, there’s no advantage in buying an air purifier that is the fastest in its category at delivering average-quality air. 

So while the Clean Air Delivery Rate is impressive and competitive on all our units, it’s not what sets them apart. 

What really matters is the air quality an air purifier can obtain. In that respect, the performance of our Max2 filter system is peerless. Our Active Carbon Filter and Green TrueHepa technology capture the smallest bacteria, mold, and virus particles—whatever the size of your space.   

Features That Enhance Air Purifier Performance

We also understand that most people don’t simply want to switch on their air purifier and leave it to run for the rest of the day at the same speed. Not only is that inviting a formidable electricity bill, but it’s also reducing the longevity of your filter for no tangible benefit. 

That’s why we incorporate real-time monitoring into our units so that your filtration is working hardest when it’s needed most. You can also enjoy smart mode, which switches between our pre-set modes (i.e. auto, eco or sleep) automatically. 

In short, you don’t need to bring your calculator out to determine the size of the air purification unit you need for your home or office. We’ve run the lab tests and have sorted the selection accordingly. Tell us the coverage you require today, and we’ll show you the model that’s more than a match for the task. 




1Coway air purifiers have been proven to trap dust, pollen, dander, viruses and bacteria in the air based on KCL (Korea Conformity Laboratories) testing.They have been tested in a 30㎥ size chamber according to the Korea Air Cleaning Association standard (SPS-KACA 002-132:2022 Modified) to measure the 0.01㎛ size of particle removal rate. It was tested on maximum airflow speed in normal room temperature and humidity conditions. The performance may vary in the actual living environment of customers.
→ Tested with Airmega Aim, 100, 150, 160, AP-1216L, AP-1512HH, AP-1512HHS, 200M, Icon, IconS, 230, 240, 250, 250 Art, 250S, 300, 300S, 400, 400S, ProX

299.97% of viruses, bacteria, fungi and pollen were verified to be removed from the air for Coway air purifiers which have Green True HEPA™ filter applied based on the Japan Food Research Laboratories(JFRL) testing according to JEM 1467 standard.
→ Tested with Coway Airmega AP-1512HH, AP-1512HHS, 250, 250 Art, 250S, 300, 300S, 400, 400S
→ All tested by JFRL and received above result within below time.

All tested by JFRL and received above result within below time.

- Virus: Tested with Escherichia coli phage ΦX174 NBRC 103405, 60 minutes
- Bacteria: Tested with Staphylococcus epidermidis NBRC 12993, 60 minutes
- Fungi/Mold: Tested with Penicillium citrinum NBRC 6352, 60 minutes
- Pollen: Tested with Cedar Pollen extract, 60 minutes

3Aerosol test conducted in a Biosafety level 3 laboratory with two Coway air purifier models, Coway Airmega 250 and 400 for removal of SARS-CoV-2 Aerosol by US based MRI Global, a not-for-profit laboratory and partner of US Department of Defense. The test was conducted in a 13.1ft3 chamber. Virus was aerosolized for 15 minutes and the product was turned on high for 2 minutes. Result showed each product effectively removed over 99.98% of the SARS-CoV-2 in 2 minutes. This is a result from a laboratory experiment condition and result may vary in different conditions. This result does not imply it kills SARS-CoV-2 or prevents the transmission of Covid-19. Coway Airmega 250S and 400S are identical to the tested models and has equal performance with an additional mobile connectivity function.

4The concentration of ammonia, acetaldehyde and acetic acid were proven to be removed within 30 minutes by FCG Research Institute, Inc. Human Life Science Lab. It is not a demonstration result in the actual use space. Not all odors and gases may be supported. → Tested with Coway Airmega 150, 160, AP-1512HH, AP-1512HHS, 400, 400S

5The coverage area of the air purifier is based on an area where the air cleaner can make two air changes per hour (ACPH). An air change per hour translates to how many times an air purifier can clean an area, assuming the height of a ceiling to be 8 ft, in one hour. Therefore ** means two air changes per hour means that the cleaner can clean the area once every 30 minutes and * means air changes per hour means that the air purifier can clean the area once every 60 minutes.

10Terms and conditions apply. Discounts, including promotions, coupons, bundle discount and subscription discount, cannot be stacked on top of other coupons. During promotional periods, discount codes will not be able to be applied to orders. Promo codes may apply to products only—filters, accessories, and new products within 3 months of the release date are not included.