When shopping for air purifiers, you may have come across the acronym, CADR. But what is CADR? CADR stands for ‘Clean Air Delivery Rate,’ and it might be more important than you think. Let’s explore why it’s good to know the CADR (and how it was assessed) before you bring a new air purifier into your home.

CADR Rating Explained

So, what is the CADR rating? A CADR rating reflects the volume of air in Cubic Feet Per Minute (CFM) that is cleaned of particles. In layman’s terms, a CADR could be understood as the effectiveness of an air purifier in removing contaminants over a specific period of time.

This standardized system is used to assess residential air purifiers. Formerly, just CFM was assessed, which only investigated how much air could be processed by a specific unit. Knowing the CADR—how much air is cleaned by an air purifier— is great for us consumers, because it makes it easy to compare different systems to find the best air purifier for your space.

However, sometimes you have to take a brand’s reported CADR with a grain of salt. Not all companies have the studies to back up their CADR measurements. Worse, some brands avoid disclosing their CADR ratings at all!

That said, it’s crucial that a brand makes it easy to find the CADR for their air purifiers. Similarly, they should be transparent when it comes to how those ratings were assessed. In the United States, there are only two laboratories authorized to perform CADR testing: SGS/IBR laboratories and Intertek.

How is a CADR Rating Calculated?

Verified to the Association of Home Appliance Manufacturers (AHAM) standard, CADR ratings are tested using a standardized method. An air purifier is placed in a test chamber 1,008 cubic feet in size. This is the same volume as a 12-foot by 12-foot room that has a 7-foot ceiling. Using monitoring devices, the amount of contaminants in the test chamber are measured.

Three types of pollutants are investigated: smoke, pollen, and dust. These are assessed because they represent particles that are small, medium, and large in size, respectively. Each of these pollutants have limits for their ratings:

  • Tobacco smoke (small particles): 10 to 450 CADR
  • Dust (medium particles): 10 to 400 CADR
  • Pollen (large particles): 25 to 450 CADR

Typically, this assessment will report on the three individual CADR ratings, as well as an overall CADR rating. While they are helpful in evaluating an air purifier’s efficiency for these three pollutants, know that CADR ratings do not measure other contaminants, like bacteria, viruses, ozone, or volatile organic compounds (VOCs).

Also, note that the CADR rating is measured while the air purifier is running on its highest fan speed setting. If you plan to use a lower fan speed, then you can assume a slightly lower CADR rating. Similarly, CADR ratings are measured using clean, new filters. That said, you could also expect your CADR performance to decrease over time—a good reminder to change your filters regularly!

How to Find the Best CADR for Your Space

The higher the CADR rating, the more effective the air purifier is and the quicker it’s able to remove contaminants from the air in a room. However, the highest CADR rating isn’t necessarily what you need for your space. A higher CADR rating might be far more than what you need, and may generate excess noise and require unnecessary energy.


That said, it’s recommended that you find an air purifier with a CADR that’s at least two-thirds of the room’s area. 


Considering a room that’s 10-feet by 16-feet, for example, the area would be its length multiplied by its width (16 x 10). So, for a room with an area of 160 square feet, you’d want a CADR rating that’s two-thirds of 160, or at least 107.

What is the CADR for AirDoctor Purifiers?

The three AirDoctor models have been independently tested by Intertek laboratories for CADR. Assessing the smallest, most dangerous particle, their smoke CADR ratings are as follows:

  • The CADR for AirDoctor 1000 is: 152
  • The CADR for AirDoctor 2000 is: 340
  • The CADR for AirDoctor 3000 is: 340
  • The CADR for AirDoctor 5000 is: 534

Let’s look at the AD3000’s CADR of 340 another way. This rating means that there’s a reduction of smoke particles to the same concentration that would be achieved by adding 340 cubic feet of clean air each minute.

According to Consumer Reports, CADR ratings from 120-179 are deemed Very Good, and anything above 240 is considered Excellent.

Final Thoughts on CADR

Consider yourself a CADR expert! You now know that it’s the best way we’re able to compare air purifiers based on their efficiency in removing three common contaminants: dust, pollen, and smoke. When you bring a new AirDoctor model into your home, be sure that it has a CADR at least two-thirds of your room’s area. We’re here to clear the air—and clear up any topics that might lead to confusion, like CADR ratings!

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