Solved! What Is a CADR Rating?

Learn what CADR ratings mean and how they relate to an air purifier’s effectiveness.

By Deirdre Mundorf | Published Oct 18, 2021 5:20 PM

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Q: I’m shopping for a new air purifier for my home and have noticed that many models list a CADR rating. What is CADR and is it something I should pay attention to when shopping? 

A: CADR ratings can be tricky to understand. Some air purifier manufacturers don’t even provide CADR ratings for their models, which can make shopping for and comparing different air purifiers yet more complicated. In short, the CADR rating indicates how effective an air purifier is at removing pollutants from the air. Comparing the CADR ratings of different air purifiers can help you select the most powerful and effective unit for your space. Continue reading to learn more about what CADR ratings mean and how they can help you narrow down your search for an air purifier.

CADR stands for Clean Air Delivery Rate.

The CADR rating specifies how quickly an air purifier is able to remove contaminants, such as dust, pollen, and smoke, from the air in a room. Air purifiers with higher CADR ratings will be able to clean the air in a space more quickly than models with a lower CADR rating.

CADR ratings are one of the most important metrics to consider when shopping for an air purifier. They can help you select the best model given the volume of your space.

Prior to the development of CADR ratings, CFM (cubic feet per minute) ratings were used to compare air purifiers. However, CADR ratings are better indicators of effectiveness because they indicate how much air will actually be cleaned, while CFM only indicates how much air a unit can process.

The AHAM (Association of Home Appliance Manufacturers) uses a standard room size and runtime to verify CADR for air-cleaning products.

Air purifiers with an AHAM-verified CADR rating are tested using a standardized method. The air purifier is placed in a test chamber with a volume of 1,008 cubic feet—in other words, the volume of a 12-foot by 12-foot room with a 7-foot ceiling. Monitoring devices in the test chamber measure the amount of dust, pollen, and smoke contaminants in the space.

As the air purifier runs at full speed, the amount of dust, pollen, and smoke contaminants continues to be monitored. The air purifier’s CADR rating is calculated based on the amount of time it took the unit to purify the air.

The CADR should equal at least two-thirds of the room’s area.

While it may be tempting just to buy an air purifier with the highest CADR rating, that might be more than you need. Instead, use the square footage of your space to determine the appropriate CADR rating for your air purifier. Look for one with a CADR rating that is approximately two-thirds of the room’s area.

To calculate the area of the room, multiply the length and width of the space. For example, the area of a 12-foot by 16-foot room is 192 square feet (12 x 16). Two-thirds of 192 is 128, so for that room you would want an air purifier with a CADR rating of at least 128.

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CADR ratings measure the level of three common contaminants: dust, pollen, and smoke.

The AHAM testing process described above produces an overall CADR rating as well as individual CADR ratings for dust, pollen, and smoke. Comparing these CADR ratings can help you evaluate how effective an air purifier will be given your specific air-cleaning needs. The maximum CADR rating for smoke and pollen is 450, and the maximum rating for dust is 400.

There are, however, some limitations to CADR ratings. They do not measure the removal of viruses, bacteria, ozone, or volatile organic compounds (VOCs). Additionally, air purifier CADR ratings do not indicate how effective a unit is at eliminating gases or odors in a space.

Lower fan speed and particle buildup on the filter over time will result in diminished CADR.

CADR ratings indicate how effective brand-new air purifiers are at cleaning the air while running on a high fan speed. Over time, the air purifier’s filter will collect particles. This will decrease its effectiveness, resulting in decreased CADR.

Additionally, running the air purifier at a lower fan speed will also result in less effective pollutant removal. Because testing measures the effectiveness of each unit when running at its highest speed, if you choose a lower fan speed, you should not expect the air purifier’s performance to match its CADR rating.

These are the best air purifiers you can buy right now: 

If you’re trying to remove smoke, allergens, mold, or pet dander from your space, try one of the air purifiers featured below, all of which have high CADR ratings.

For Smoke

One of the best air purifiers for smoke is the Bissell air320 Smart Air Purifier. Despite its “Best for Bedrooms” award, this air purifier can be used in any room of the house. It boasts a CADR rating of 211 for smoke, along with ratings of 245 for pollen and 221 for dust. This model uses a three-stage filtration process with a prefilter, an activated carbon filter, and a HEPA filter to effectively remove 99.97 percent of particles as small as 0.3 microns from the air. The air purifier features color-coded readings of the indoor air quality and offers five different fan speeds.

Get the Bissell air320 Smart Air Purifier on Amazon for $329.99

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For Allergies

Effectively remove dust and pollen from your space with the Coway AP-1512HH HEPA Air Purifier. This air purifier uses a True HEPA filter that removes up to 99.97 percent of particles from the air to provide relief for allergy sufferers. Its ability to help individuals breathe more easily, even while sleeping, helped it earn the “Best for Bedrooms” award. This model has a 246 dust CADR rating, 240 pollen CADR rating, and 233 smoke CADR rating. A few other notable features of the air purifier include its pollution sensor and LED air quality indicator light, three fan speeds, a timer feature, and filter replacement indicator lights.

Get the Coway AP-1512HH HEPA Air Purifier on Amazon for $220.15

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For Mold

The Germ Guardian Air Purifier is an excellent choice for those looking for an air purifier to eliminate mold spores and odors from their home. Given the “Best for Odor Control” award, this air purifier also has very high CADR ratings (239 for dust, 237 for pollen, and 235 for smoke). The True HEPA air filter works to eliminate up to 99.97 percent of mold spores, dust, pollen, and other pollutants that are as tiny as 0.3 microns. This model also features an activated charcoal filter to reduce odors and a UV-C light to eliminate airborne viruses.

Get the Germ Guardian Air Purifier on Amazon for $179.95

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For Pet Owners

Pet owners may find the RabbitAir MinusA2 HEPA Air Purifier to be the best fit for their needs. This model uses a six-stage air purification and deodorization process to effectively purify the air in a home. With its CADR ratings of 200 for pollen, 193 for dust, and 180 for smoke, you can feel confident that this air purifier will quickly and efficiently remove a range of particles, including pet dander. Additionally, RabbitAir includes a customized filter with each purifier, and pet owners can select the special pet allergy filter. This feature earned this model the “Best for Allergies” award for the best air purifiers for pets.

Get the RabbitAir MinusA2 HEPA Air Purifier on Amazon for $599.95

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The prices listed here are accurate as of publication on 10/18/21.