CFM (Cubic Feet per Minute)
CFM (Cubic Feet per Minute) measures the volume of air that flows through an air purifier or ventilation system. It's a critical specification that determines how quickly an air purifier can process the air in your room.
CFM directly impacts air changes per hour (ACH) - the number of times all air in a room is filtered hourly. For optimal air quality, you want 4-6 air changes per hour. Calculate required CFM by: (Room Volume ÷ 60 minutes) × desired ACH. For example, a 12x15 room with 8-foot ceilings (1,440 cubic feet) needs 96-144 CFM for 4-6 ACH. DIY box fan air purifiers typically deliver 200-400 CFM.
CFM measures air volume processed per minute
Higher CFM = more air cleaned in less time
Calculate needed CFM: (Room sq ft × ceiling height ÷ 60) × desired ACH
Target 4-6 air changes per hour (ACH) for healthy indoor air
Standard box fans provide 200-400 CFM at medium-high speeds