# Clean Air Delivery Rate (CADR)

This is thought to be the most meaningful assessment of an air purifier. It is the amount of pure air produced by the air purifier per unit time. It takes into account both the amount of air pushed through the air purifier by the fan per unit time and also the efficiency of the filter. As the efficiency of a filter varies to some extent with particle size, it can be different for different types of pollution.

Supposing an air purifier has 50 cubic feet of air going through it per minute-

If the filter is 90% efficient, the CADR is =50 x 0.9 = 45 cuft per minute, If the filter is 70% efficient, the CADR is =50 x 0.7 = 35 cuft per minute

The formulae used to calculate the CADRs are-

**CADR** (cfm)= [(L x W x H x ACH) / 60]**CADR** (m3/hour) = (CADR in cfm)/0.59

cfm=cubic feet per minute

m3/hr=cubic meters per hour