Atmosphere (atm)
The atmosphere, symbol atm, is a pressure unit originally based on average sea-level air pressure on Earth, defined as 101,325 pascals. First used in the 19th century for meteorology and engineering, the atmosphere is a convenient unit of measurement for expressing pressure in science, including chemistry, physics, and gas laws. Though largely replaced by SI units in formal texts, it remains widely recognized in academia and industry. Its historical role and practical magnitude sustain its relevance in global pressure measurements.
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.