Full form of psi

Answer 1

"Psi" says the formula. The pound per square inch or, more accurately, pound-force per square inch - symbol: psi or lbf/in2 or lbf/in2 - 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.

1 pound per square inch = 6 894.75729 pascals

Pascal (Pa) is the SI unit of pressure.