CADR stands for Clean Air Delivery Rate. The rate provides you with information on the number of particles that need to be extracted from the air in the room.

If you’ve been searching for an air purifier, the CADR rating is something that you may have come across. Maybe you’ve been a little confused as to what this rating means and how it can affect the performance of an air purifier. 

The purpose of this post is to provide you with the information you need to feel more confident about the role of CADR ratings and air purifiers. 

What are CADR Ratings?

The CADR rating is a useful numerical value that you can use to determine the speed at which an air purifier is able to eliminate potentially harmful particles from the room. 

If you have a larger room and the CADR rating is too low, it will take longer to purify the air. Therefore, the CADR rating is a vital feature to consider to make sure that you’ve got an air purifier that’s right for the size of the room you’re planning to use it in. 

CADR ratings are available in Cubic Feet per Minute (CFM). Alternatively, it may also be measured in  m³/ hour. 

The main particles you can use the CADR rating to measure include dust, pollen, and smoke. These ratings are useful in measuring pollutants due to how small and harmful they can be. 

Accuracy of CADR Ratings

To find out the accuracy of CADR ratings, there’s a procedure performed that’s known as the ANSI/AHAM AC-1 test.

The test is usually carried out by the Association of Home Appliance Manufacturers (AHAM). They take a measurement of the air before leaving the purifier turned on in an area with unwanted particles. 

After 20 minutes, the air purifier is turned off and another measurement of the air is taken as a comparison. They’re then able to get a reading on the CADR rating. 

However, we recommend that you take these ratings as a guideline on how effective a device is at purifying the air. 

This is because the air purifiers have been tested with brand new motors and they haven’t been through any real use. When it comes to using an air purifier at home, it will likely decline in its ability to filter pollutants over time. 

How to Use CADR Ratings

To get a better idea of the CADR rating ranges for the different pollutants, take a quick look below:

  • Smoke – 10 to 450 CADR rating
  • Dust – 10 to 400 CADR rating
  • Pollen – 24 to 450 CADR rating 

You’ll want to keep an eye out for these CADR ratings to make sure that you’ve chosen a purifier that fulfills your needs properly. 

For example, the more susceptible you are to allergies from pollen, the higher you’d want the pollen CADR rating to be. 

Quick Tips

  • CADR ratings don’t provide you with the total ability of the air purifier, only the capacity it can clean at. 
  • We recommend that you look out for air purifiers with the AHAM rating. These are purifiers that have met or exceeded a specific criteria to ensure the CADR rating is accurate (with new air purifiers). 
  • The tests for CADR ratings are performed with brand new filters. Therefore, it’s likely that the CADR rating will decrease over time. 
  • We recommend using the CADR rating as one of the factors to take into consideration when choosing an air purifier. You’ll also want to think about the noise level, safety, motor, and more.  
  • If you’ve found an air purifier with low airflow and great filtering features, a good CADR rating can be useful in keeping the device effective.  


  • CADR ratings are found through strict procedures 
  • Useful for people with allergies
  • Helps you compare air purifiers


  • Limited to measuring dust, pollen & smoke
  • No information on the size of particles being filtered 
Does a larger air purifier mean improved CADR ratings?

The more surface area that’s available with an air purifier, the better its ability to have a higher CADR rating is. In particular, air purifiers that have a box design have higher CADR ratings than ones with a thinner design.

Is the CADR rating an indication of the noise level?

Noise level is not something that AHAM are looking at when testing CADR ratings. Therefore, CADR ratings and noise levels aren’t closely related.

What’s an ACH rating?

ACH refers to Air Changes per Hour. This rating lets you know the number of times your air purifier is able to filter particles in the air of a room.