Pounds per Square Inch (psi or lb/in²)

Pounds or pound force per square inch (psi, lb/in², pfsi or lbf/in²) is a widely used British and American unit of measure for pressure. 1 psi equals 6,894.76 pascals.

In the USA, the psi pressure unit is the primary unit of measure for pressure and almost all pressure instruments are specified and displayed in pounds per square inch.

The psi is still used extensively in the UK but the bar pressure unit has mostly replaced it as the primary pressure unit.