Definition: Kip per square inch (symbol: ksi) is a unit of pressure equal to 1,000 psi (pounds per square inch).

History/origin: The kilopound per square inch is a practical unit derived from the pound per square inch (psi) to express large pressures in a more manageable form. It simplifies calculations and reduces the number of digits needed.

Current use: ksi is used in structural engineering, material science, and other fields where large pressures or stresses are involved. It is common for describing the tensile strength and yield strength of materials such as steel and concrete.