Breathe Clean Air



Clean Air Delivery Rate

(CADR) Calculator


What is CADR?


Clean Air Delivery Rate (CADR) indicates the volume of filtered air an air cleaner delivers. CADR is the product of efficiency and airflow. Effectiveness takes into account how much of the air you’re cleaning. An air cleaner that is 100% efficient at cleaning 300 cfm of air would have a CADR of 300. An air cleaner that is 90% efficient at cleaning 1,000 cfm of air would have a CADR of 900, and be 3-times as effective. CADR provides you with a metric for comparing various systems.

Use our CADR Calculator. Simply enter the airflow and efficiency of the air cleaner:


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More Info About CADR

The output shows the clean air delivery rate, CADR, and the percentage of a bus’s air conditioning system that is cleaned. To put the CADR number in terms people can relate to the calculator also shows how the CADR amount compares to a typical handheld hairdryer, which is 80 cfm. For example, if you calculate a CADR of 350 for your 66-person bus, do you think that only supplying 4 hair dryers of clean air is enough for 67 people? Likely not. In this case, you’d want to install several systems.

The CDC and ASHRAE recommend supplementing filtration with UVC germicidal air cleaning.

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