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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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| These witty workplace labels from Safety Emporium are a fun way to relieve workplace pressures. |
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that causes the Hg column to rise 1 millimeter is called a torr (you may still see the term 1 mm Hg used; this has been replaced by the torr.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. |
Disclaimer: The information contained herein is believed to be true and accurate, however ILPI makes no guarantees concerning the veracity of any statement. Use of any information on this page is at the reader's own risk. ILPI strongly encourages the reader to consult the appropriate local, state and federal agencies concerning the matters discussed herein.