The pound per square inch or, more accurately, pound-force per square inch / pressure per square inch is a unit of pressure or of stress based on avoirdupois units. It is the pressure resulting from a force of one pound-force applied to an area of one square inch: Using unit conversion: 1 psi = ≈ 6894.757293168 N/m² Therefore, one pound per square inch is approximately 6894.757 Pa.