Non-SI units mentioned in the SI
This is a list of units that are not defined as part of the International System of Units (SI), but are otherwise mentioned in the SI[1][2], because either the General Conference on Weights and Measures (CGPM) accepts their use as being multiples or submultiples of SI-units, they have important contemporary application worldwide, or are otherwise commonly encountered worldwide.
Units officially accepted for use with the SI
Common units not officially sanctioned
Name |
Symbol |
Quantity |
Equivalent SI unit |
Ångström, angstrom |
Å |
length |
1 Å = 0.1 nm = 10−10 m |
nautical mile |
nm |
length |
1 nautical mile = 1852 m |
knot |
kt |
speed |
1 knot = 1 nautical mile per hour = (1852 / 3600) m / s |
are |
a |
area |
1 a = 1 dam2 = 100 m2 |
barn |
b |
area |
1 b = 10−28 m2 |
bar |
bar |
pressure |
1 bar = 105 Pa |
millibar |
mbar |
pressure |
1 mbar = 1 hPa = 100 Pa |
atmosphere |
atm |
pressure |
1 atm = 1013.25 mbar = 1013.25 hPa = 101,325 Pa exactly (commonly used in atmospheric meteorology, in oceanography and for pressures within liquids, or in the industry for pressures within containers of liquified gas) |
dyne per square centimeter (barye) |
Ba |
pressure |
1 Ba = 0.1 Pa = 0.1 N/m2 = 100 g·cm−1s−2 |
Pounds per square inch |
psi |
pressure |
1 psi = 6,894.757 Pa = 6.894757 kPa = 6,894.757 N/m2 = 6.894757 Mg·cm−1s−2= 6894.757 kg·cm−1s−2 |
Inch of Mercury |
inHg |
pressure |
1 inHg = 3386.389 Pa at 0 °C = 3.386389 kPa at 0 °C = 3386.389 N/m2 at 0 °C = 3.386389 Mg·cm−1s−2= 3386.389 kg·cm−1s−2 |
Millimetre of mercury |
mmHg |
pressure |
1 mmHg = 133.322387415 Pa at 0 °C = 133.322387415 N/m2 at 0 °C = 133.322387415 kg·cm−1s−2 at 0 °C |
torr |
Torr |
pressure |
1 Torr = 133.322368421... Pa = 133.322368421... N/m2 = 133.322368421... kg·cm−1s−2 |
See also
References
- ^ "Non-SI units accepted for use with the SI, and units based on fundamental constants" (PDF). SI brochure (8th edition). BIPM. http://www.bipm.org/en/si/si_brochure/chapter4/4-1.html. Retrieved 2010-08-28.
- ^ Taylor, Barry N. (ed.) (2001). "The International System of Units (SI)". Special Publication 330. Gaithersburg, Maryland: National Institute of Standards and Technology (NIST). http://physics.nist.gov/Pubs/SP330/sp330.pdf.
- ^ International Bureau of Weights and Measures (2006), The International System of Units (SI) (8th ed.), p. 126, ISBN 92-822-2213-6, http://www.bipm.org/utils/common/pdf/si_brochure_8_en.pdf
- ^ ISO 80000
- ^ The IAU Style Manual (1989): The Preparation of Astronomical Papers and Reports, p. 23, http://www.iau.org/static/publications/stylemanual1989.pdf
- ^ In this case it is not the speed of light, but the length of the meter that is obtained by experiment
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Base units |
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Derived units |
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Accepted for use
with SI |
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See also |
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Book:International System of Units · Category:SI base units
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