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Pressure Unit Conversions |
Here is a handy conversion calculator for some common pressure terms. The definitions of each term are in the following section.
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If you are unfamiliar with the terms used in these definitions, see our mass unit and distance unit conversion pages.
Unit | Equivalent measurements, comments | |
---|---|---|
Pounds per square inch (psi, PSI, lb/in^{2}, lb/sq in) | Commonly used in the U.S., but not elsewhere. Normal atmospheric pressure is 14.7 psi, which means that a column of air one square inch in area rising from the Earth's atmosphere to space weighs 14.7 pounds. | |
Atmosphere (atm) | Normal atmospheric pressure is defined as 1 atmosphere. 1 atm = 14.6956 psi = 760 torr. | |
Torr (torr) | Based on the original Torricelli barometer design, one atmosphere of pressure will force the column of mercury (Hg) in a mercury barometer to a height of 760 millimeters. A pressure that causes the Hg column to rise 1 millimeter is called a torr (you may still see the term 1 mm Hg used; this has been replaced by the torr. "mm Hg" is commonly used for blood pressure measurements). 1 atm = 760 torr = 14.7 psi. | |
Bar (bar) | The bar nearly identical to the atmosphere unit. One bar = 750.062 torr = 0.9869 atm = 100,000 Pa. | |
Millibar (mb or mbar) | There are 1,000 millibar in one bar. This unit is used by meteorologists who find it easier to refer to atmospheric pressures without using decimals. One millibar = 0.001 bar = 0.750 torr = 100 Pa. | |
Pascal (Pa) | 1 pascal = a force of 1 Newton per square meter (1 Newton = the force required to accelerate 1 kilogram one meter per second per second = 1 kg^{.}m/s^{2}; this is actually quite logical for physicists and engineers, honest). 1 pascal = 10 dyne/cm^{2} = 0.01 mbar. 1 atm = 101,325 Pascals = 760 mm Hg = 760 torr = 14.7 psi. | |
Kilopascal (kPa) | The prefix "kilo" means "1,000", so one kilopascal = 1,000 Pa. Therefore, 101.325 kPa = 1 atm = 760 torr and 100 kPa = 1 bar = 750 torr. | |
Megapascal (MPa) | The prefix "mega" means "1,000,000", so one megapascal = 1,000 kPa = 1,000,000 Pa = 9.869 atm = 145 psi. | |
Gigapascal (GPa) | The prefix "giga" means "1,000,000,000", so one gigapascal = 1,000 MPa = 1,000,000 kPa = 1,000,000,000 Pa = 9,870 atm = 10,000 bar. Pressures of several gigapascals can convert graphite to diamond or make hydrogen a metallic conductor! Such high pressures are rarely encountered in everyday life. |
Entry last updated: Wednesday, August 10, 2016. This page is copyright 2000-2016 by ILPI. Unauthorized duplication or posting on other web sites is expressly prohibited. Send suggestions, comments, and new entry desires (include the URL if applicable) to us by email.
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