CFM (cubic feet per minute) is calculated this way: air speed X area . The amount of air depends on some other factors as well, such as the diameter and shape of the blades, speed at which the blades turn (revolutions per minute or rpm), horsepower (hp) of the motor, and overall fan design. These combined factors establish the air moving capacity of a fan. any carbon filter also has a CFM that can handle max! so your carbon filter CFM should be equal or higher then the fan CFM to have an optimum odor controlling.
CFM(FAN) = CFM(FILTER) or CFM(FAN) < CFM(FILTER)