torr

unit of measurement

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July 14, 2026

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The torr is a unit of pressure, equivalent to 1/760 of an atmosphere. It is approximately equal to 133.3 pascals. This unit was named in honor of Evangelista Torricelli, an Italian physicist and mathematician who invented the mercury barometer. Torricelli is credited with creating the first sustained vacuum and understanding that variations in mercury height in a tube were due to changes in atmospheric pressure. The pascal (Pa) is the standard SI unit for pressure, with one pascal being equal to one newton per square meter. Due to its small size, the kilopascal (kPa) is more commonly used, with standard atmospheric pressure being 101.325 kPa.1234

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vacuum technology
…apparently different units, a term, torr, has been postulated; one standard atmosphere = 760 torr (1 torr = 1 mm Hg). This term was replaced in 1971 by an SI unit defined as the newton per square metre (N/m²) and called the pascal (one pascal = 7.5 × 10^-3 torr).
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…apparently different units, a term, torr, has been postulated; one standard atmosphere = 760 torr (1 torr = 1 mm Hg). This term was replaced in 1971 by an SI unit defined as the newton per square metre (N/m²) and called the pascal (one pascal = 7.5 × 10^-3 torr).
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