As such, the prototype pound at the time was known as the avoirdupois wool pound.Ĭurrent use: The psi is fairly widely used to measure numerous pressures, such as tire pressure, scuba tank pressure, natural gas pipeline pressure, among others. The system is believed to have come into use in England around 1300 and was used in the international wool trade. It is based on the avoirdupois system, a system that uses weights in terms of the avoirdupois pound, which was standardized in 1959. History/origin: Pound-force per square inch is a unit that originated in the imperial and US customary systems of units. One psi is approximately 6,895 pascals (N/m 2). It is defined as the pressure that results when a force of one pound-force is applied to a one-square-inch area. Pound-force per square inchĭefinition: A pound-force per square inch (symbol: psi) is an imperial and US customary unit of pressure based on avoirdupois units. This is true of most countries, including the United States. The kilopascal is more prevalent in scientific contexts such as material science, engineering, and geophysics. Exceptions include certain countries that use either the imperial or United States customary systems of measurement, such as the United States, in which the unit of pound per square inch is more commonly used. In 1971, at the 14 th General Conference on Weights and Measures, the pascal was adopted as an SI derived unit of pressure.Ĭurrent use: The kilopascal is widely used worldwide in countries that have adopted SI. The kilopascal is simply a multiple of the pascal, as is common within SI. History/origin: The unit, pascal, is named after Blaise Pascal, a French mathematician and physicist. A kilopascal is defined as 1,000 Pa, where 1 Pa is defined as the pressure exerted by a 1 newton force applied perpendicularly to an area of one square meter, expressed as 1 N/m 2 or 1 kg/m Definition: A kilopascal (symbol: kPa) is a multiple of the pascal (Pa), an SI (International System of Units) derived unit of pressure used to measure internal pressure, Young's modulus, stress, and ultimate tensile strength.

Psi to kpa chart