Pounds per Square Inch (psi)
The pound per square inch, symbolized as psi, is an imperial pressure unit defined as one pound-force per square inch. It originated in the United States and the UK for industrial, automotive, and engineering uses. Psi remains the standard for tire pressure, hydraulic systems, and pipelines in countries that use the imperial system. Its frequent application in daily contexts and need for conversion with metric units underscore the importance of precise metric-imperial conversions in trade, safety, and engineering.
Pascal (Pa)
The pascal (Pa) is the official SI unit for pressure, defined as the force of one newton applied over an area of one square meter. This unit was named in honor of Blaise Pascal, a renowned French mathematician and physicist, and formally adopted in 1971 to harmonize pressure measurement standards around the world. The pascal is widely used in scientific, industrial, and engineering fields, particularly in disciplines like fluid dynamics and atmospheric science. Because a single pascal is a small unit of pressure, larger multiples such as the kilopascal are commonly employed for practical purposes. The introduction of the pascal helped achieve uniformity and accuracy in reporting pressure across different sectors globally.