Kilopound per Square Inch (ksi)

A unit of pressure equal to 1,000 pounds per square inch, common in structural engineering

The Kilopound per Square Inch (ksi) is a unit of pressure with a history connected to the study of fluids, gases, and atmospheric phenomena. Evangelista Torricelli's invention of the barometer in 1643 was a landmark in pressure measurement, and subsequent work by Blaise Pascal established the mathematical foundations. The pascal — the SI unit — was named in Pascal's honor when the SI system was formalized. The Kilopound per Square Inch reflects either the SI tradition or the practical conventions of specific industries that standardized their measurements independently.

Accurate pressure measurement is critical in engineering, science, commerce, and everyday life. Using the correct unit and applying conversions precisely prevents errors that can be costly or dangerous in professional applications.

Conversion Table

UnitSymbol1 ksi =
PascalPa6894760 Pa
KilopascalkPa6894.76 kPa
Barbar68.9476 bar
Atmosphereatm68.046 atm
Pound per Square Inchpsi1000 psi
Millimeters of MercurymmHg51715.1 mmHg
MegapascalMPa6.89476 MPa
GigapascalGPa0.00689476 GPa
Torrtorr51715.1 torr
Inch of MercuryinHg2036.02 inHg
Kilogram-force per Square Centimeterkgf/cm²70.307 kgf/cm²

Conversions Involving Kilopound per Square Inch

Common Uses of the Kilopound per Square Inch

  • Automotive — inflating tires to manufacturer-specified pressures
  • Weather reporting — tracking barometric pressure for forecasting
  • Hydraulic systems — designing and operating fluid power equipment
  • Scuba diving — calculating safe dive depths based on partial pressures
  • Medical — measuring blood pressure and calibrating medical equipment

Did You Know?

The deepest point in the ocean — the Challenger Deep in the Mariana Trench — has a water pressure of approximately 110 MPa, or about 1,086 times standard atmospheric pressure. The Kilopound per Square Inch is one of several units used to express pressures across this extraordinary range.