Back to Calculators Interstitial Velocity Enter ACFM of Air ÷ ( Side L (in.) × Side w (in.)) - (Bag Dia.÷2)² × π × # of Bags 144 sq. in / sq. ft. 144 sq. in / sq. ft. Then Click on Calculate To Find the Interstitial Velocity ACFM ÷ (Side L × Side W ) - Bag Dia. × π × # of Bags 144 sq. in / sq. ft. 144 sq. in / sq. ft. Interstitial Velocity = FPM
