Pound per square inch

The pound per square inch (psi or lbf/in2) is a widely used unit of pressure in engineering, physics, and industry. It provides a way to quantify the force exerted by a fluid, gas, or liquid on a given area, allowing for accurate measurements in various applications.

Definition and Usage

Pound per square inch is defined as the pressure resulting from a force of one pound-force applied uniformly over an area of one square inch. This unit is valuable for expressing pressure in systems where forces are distributed over small areas.

Importance in Engineering and Industry

Pound per square inch is essential in many fields:

  • Engineering: Engineers use psi to assess stress in materials and design structures.
  • Fluid Mechanics: It's used to measure pressure in fluid systems and hydraulic machinery.
  • Tire Pressure: PSI is commonly used to indicate tire pressure in vehicles.

Conversions and Equivalents

Knowing the conversions of psi to other pressure units is valuable:

  • 1 Pound per Square Inch (psi) = 6894.76 Pascal (Pa)
  • 1 Pound per Square Inch (psi) ≈ 0.068948 Bar
  • 1 Pound per Square Inch (psi) ≈ 51.71493 Torr
  • 1 Pound per Square Inch (psi) ≈ 0.070307 Ksi (Kilopound per Square Inch)

Applications in Everyday Life

Pound per square inch is encountered in various practical situations:

  • Automotive: PSI is used to measure tire pressure and ensure safe driving conditions.
  • Fluid Systems: Engineers use psi to design and analyze fluid conveyance systems.
  • Hydraulic Machinery: PSI measurements are crucial in hydraulic equipment.


The pound per square inch (psi) unit is a fundamental measurement of pressure, serving as a versatile tool in engineering, industry, and everyday life. Its ability to quantify the force applied on a specific area provides insights into stress distribution, fluid behavior, and design considerations.

Keywords: Pound per Square Inch, psi, pressure unit, engineering, fluid mechanics, tire pressure, conversions