Torr (mmHg)
The torr, symbolized as Torr, is a pressure unit equal to 1/760 of a standard atmosphere, approximately 133.322 pascals. Named for Evangelista Torricelli, inventor of the mercury barometer, the torr was historically central in vacuum measurement and laboratory work. This unit offers a practical scale for low pressures, particularly in physics and chemistry. While mostly replaced by SI units, such as the pascal, the torr remains essential in high-precision scientific instruments and measurements worldwide.
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.