Air Purifier CADR Calculator Length Breadth Height Enter room size in Sq. Ft. or Sr. Mt. Sq. Ft. Sr. Mt. Air Changes per Hour (ACH) ⓘ how many times the entire volume of air in a room is replaced with clean or filtered air in one hour. If a room has 5 ACH, the air inside that room is effectively cleaned or replaced five times every hour. Five complete room-volumes of air moving through the system. 4 ACH6 ACH8 ACH Calculate CADR
