What is the difference between SCFM and PSI?

SCFM (Standard Cubic Feet per Minute) indicates the volume of compressed air delivered by the compressor. This is the most important measure of air compressor performance. PSI (Pounds per Square Inch) is the measure of air force delivered by the air compressor. Using an air tool with a compressor requires both a minimum SCFM and adequate PSI for proper operation.