Difference between revisions of "Measurement (LINEAR) – CONVERSION"
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===Length=== | ===Length=== | ||
{| class="wikitable" | {| class="wikitable" | ||
− | |+ | + | |+ Length |
!Name of unit | !Name of unit | ||
!Symbol | !Symbol | ||
Line 85: | Line 85: | ||
!Relation to SI units | !Relation to SI units | ||
|- | |- | ||
− | | | + | | ångström || Å |
− | | ≡ | + | | ≡ 1 x 10<sup>-10</sup> m |
| ≡ 0.1 nm | | ≡ 0.1 nm | ||
|- | |- | ||
− | | | + | | astronomical unit || au |
− | | ≡ | + | | ≡ 149 597 870 700 m <br>≈ Distance from Earth to Sun |
− | | ≡ | + | | ≡ 149 597 870 700 m |
|- | |- | ||
− | | | + | | attometre || am |
− | | ≡ | + | | ≡ 1 x 10<sup>-18</sup> m |
− | | ≡ | + | | ≡ 1 x 10<sup>-18</sup> m |
|- | |- | ||
− | + | | barleycorn (H) || | |
− | | = {{ | + | | = <math> \tfrac{1}{3}</math> in (see note above about rounding) |
− | | = 8.4{ | + | | = <math> 8.4 \overline{6} \times 10^{-3}</math> m |
|- | |- | ||
− | | bohr, | + | | bohr, atomic unit of length || ''a''<sub>0</sub> |
− | | = | + | | = Bohr radius of hydrogen |
− | | ≈ | + | | ≈ 5.291 772 1092|(17) x 10<sup>-11 </sup> m |
|- | |- | ||
| cable length (imperial) || | | cable length (imperial) || | ||
− | | ≡ 608 | + | | ≡ 608 ft |
| ≈ 185.3184 m | | ≈ 185.3184 m | ||
|- | |- | ||
− | | | + | | cable length (International) || |
− | | ≡ {{ | + | | ≡ <math> \tfrac{1}{10}</math> nmi |
| ≡ 185.2 m | | ≡ 185.2 m | ||
|- | |- | ||
| cable length (US) || | | cable length (US) || | ||
− | | ≡ 720 | + | | ≡ 720 ft |
| = 219.456 m | | = 219.456 m | ||
|- | |- | ||
− | | | + | | chain (Gunter's; Surveyor's) || ch |
− | | ≡ 66 | + | | ≡ 66 ft (US) ≡ 4 rods |
− | | ≈ | + | | ≈ 20.116 84 m |
|- | |- | ||
− | | | + | | cubit (H) || |
| ≡ Distance from fingers to elbow ≈ 18 in | | ≡ Distance from fingers to elbow ≈ 18 in | ||
| ≈ 0.5 m | | ≈ 0.5 m | ||
|- | |- | ||
− | | | + | | ell (H) || ell |
− | | ≡ 45 in | + | | ≡ 45 in (In England usually) |
| = 1.143 m | | = 1.143 m | ||
|- | |- | ||
− | | | + | | fathom || ftm |
− | | ≡ 6 ft | + | | ≡ 6 ft |
| = 1.8288 m | | = 1.8288 m | ||
|- | |- | ||
− | | | + | | femtometre || fm |
− | | ≡ | + | | ≡ 1 x 10<sup>-15</sup> m |
− | | ≡ | + | | ≡ 1 x 10<sup>-15</sup> m |
|- | |- | ||
− | + | | fermi || fm | |
− | | ≡ | + | | ≡ 1 x 10<sup>-15</sup> m |
− | | ≡ | + | | ≡ 1 x 10<sup>-15</sup> m |
|- | |- | ||
| finger || | | finger || | ||
− | | ≡ {{ | + | | ≡ <math> \tfrac{7}{8}</math> in |
− | | = | + | | = 0.022 225 m |
|- | |- | ||
| finger (cloth) || | | finger (cloth) || | ||
− | | ≡ {{ | + | | ≡ <math> 4 \tfrac{1}{2}</math> in |
| = 0.1143 m | | = 0.1143 m | ||
|- | |- | ||
− | | | + | | foot (Benoît) (H) || ft (Ben) |
| | | | ||
− | | ≈ | + | | ≈ 0.304 799 735 m |
|- | |- | ||
| foot (Cape) (H) || | | foot (Cape) (H) || | ||
|Legally defined as 1.033 English feet in 1859 | |Legally defined as 1.033 English feet in 1859 | ||
− | | ≈ | + | | ≈ 0.314 858 m |
|- | |- | ||
| foot (Clarke's) (H) || ft (Cla) | | foot (Clarke's) (H) || ft (Cla) | ||
| | | | ||
− | | ≈ | + | | ≈ 0.304 797 2654 m |
|- | |- | ||
| foot (Indian) (H) || ft Ind | | foot (Indian) (H) || ft Ind | ||
| | | | ||
− | | ≈ | + | | ≈ 0.304 799 514 m |
|- | |- | ||
− | + | | foot, metric || mf | |
| ≡ 300 mm | | ≡ 300 mm | ||
| ≡ 0.3 m | | ≡ 0.3 m | ||
|- | |- | ||
− | | foot, metric ( | + | | foot, metric (Mesures usuelles) (H) |
| | | | ||
− | | ≡ {{ | + | | ≡ <math> \tfrac{1}{3}</math> m |
− | | ≡ 0.{ | + | | ≡ <math>0. \overline{3}</math> m |
|- | |- | ||
| foot (International) || ft | | foot (International) || ft | ||
− | | ≡ 0.3048 m ≡ {{ | + | | ≡ 0.3048 m ≡ <math> \tfrac{1}{3}</math> yd ≡ 12 inches |
| ≡ 0.3048 m | | ≡ 0.3048 m | ||
|- | |- | ||
| foot (Sear's) (H) || ft (Sear) | | foot (Sear's) (H) || ft (Sear) | ||
| | | | ||
− | | ≈ | + | | ≈ 0.304 799 47 m |
|- | |- | ||
| foot (US Survey) || ft (US) | | foot (US Survey) || ft (US) | ||
− | | ≡ { | + | | ≡ <math> \tfrac{1200}{3937}</math> m |
− | | ≈ | + | | ≈ 0.304 800 610 m |
|- | |- | ||
− | | | + | | french; charriere || F |
− | | ≡ {{ | + | | ≡ <math> \tfrac{1}{3}</math> mm |
− | | = 0.{ | + | | = <math> 0. \overline{3}</math> x 10<sup>-3</sup> m |
|- | |- | ||
− | | | + | | furlong || fur |
− | | ≡ 10 chains = 660 ft = 220 yd | + | | ≡ 10 chains = 660 ft = 220 yd |
| = 201.168 m | | = 201.168 m | ||
|- | |- | ||
− | | | + | | hand || |
− | | ≡ 4 in | + | | ≡ 4 in |
| ≡ 0.1016 m | | ≡ 0.1016 m | ||
|- | |- | ||
− | | | + | | inch (International) || in |
− | | ≡ 2.54 cm ≡ {{ | + | | ≡ 2.54 cm ≡ <math> \tfrac{1}{36}</math> yd ≡ <math> \tfrac{1}{12}</math> ft |
| ≡ 0.0254 m | | ≡ 0.0254 m | ||
|- | |- | ||
− | | | + | | league (land) || lea |
− | | ≈ 1 hour walk, Currently defined in US as 3 Statute miles, | + | | ≈ 1 hour walk, Currently defined in US as 3 Statute miles, but historically varied from 2 to 9 km |
− | | ≈ | + | | ≈ 4828 m |
|- | |- | ||
− | | | + | | light-day || |
| ≡ 24 light-hours | | ≡ 24 light-hours | ||
− | | ≡ | + | | ≡ 2.590 206 837 12 × 10<sup>13</sup> m |
|- | |- | ||
− | | | + | | light-hour || |
| ≡ 60 light-minutes | | ≡ 60 light-minutes | ||
− | | ≡ | + | | ≡ 1.079 252 8488 × 10<sup>12</sup> m |
|- | |- | ||
− | | | + | | light-minute || |
| ≡ 60 light-seconds | | ≡ 60 light-seconds | ||
− | | ≡ | + | | ≡ 1.798 754 748 × 10<sup>10</sup> m |
|- | |- | ||
− | + | | light-second || | |
| ≡ Distance light travels in one second in vacuum | | ≡ Distance light travels in one second in vacuum | ||
− | | ≡ | + | | ≡ 299 792 458 m |
|- | |- | ||
− | + | | light-year || ly | |
− | | ≡ Distance light travels in vacuum in 365.25 days | + | | ≡ Distance light travels in vacuum in 365.25 days |
− | | ≡ | + | | ≡ 9.460 730 472 5808 × 10<sup>15</sup> m |
|- | |- | ||
− | | | + | | line || ln |
− | | ≡ {{ | + | | ≡ <math> \tfrac{1}{12}</math> in |
− | + | | = 0.002 11<math> \overline{6}</math> m | |
− | |||
− | | = | ||
|- | |- | ||
− | | | + | | link (Gunter's; Surveyor's) || lnk |
− | | ≡ {{ | + | | ≡ <math> \tfrac{1}{100}</math> ch ≡ 0.66 ft (US) ≡ 7.92 in |
− | | ≈ | + | | ≈ 0.201 168 4 m |
|- | |- | ||
| link (Ramsden's; Engineer's) || lnk | | link (Ramsden's; Engineer's) || lnk | ||
− | | ≡ 1 ft | + | | ≡ 1 ft |
| = 0.3048 m | | = 0.3048 m | ||
|- style="background:#dfd;" | |- style="background:#dfd;" | ||
− | | | + | | metre (SI base unit)<br /><small>(meter)</small> || m |
− | | ≡ Distance light travels in {{ | + | | ≡ Distance light travels in <math> \tfrac{1}{299 792 458} </math> of a second in vacuum. |
− | | ( | + | | (SI base unit) |
|- | |- | ||
| mickey || | | mickey || | ||
Line 248: | Line 246: | ||
| = {{val|1.27|e=-4|u=m}} | | = {{val|1.27|e=-4|u=m}} | ||
|- | |- | ||
− | | | + | | micrometre (old: micron)|| μ; μm |
| ≡ {{val|1|e=-6|u=m}} | | ≡ {{val|1|e=-6|u=m}} | ||
| ≡ {{val|1|e=-6|u=m}} | | ≡ {{val|1|e=-6|u=m}} | ||
|- | |- | ||
− | | mil; | + | | mil; thou || mil |
| ≡ {{val|1|e=-3|u=in}} | | ≡ {{val|1|e=-3|u=in}} | ||
| = {{val|2.54|e=-5|u=m}} | | = {{val|2.54|e=-5|u=m}} | ||
|- | |- | ||
− | | | + | | mil (Sweden and Norway) || mil |
| ≡ 10 km | | ≡ 10 km | ||
| = {{val|10000|u=m}} | | = {{val|10000|u=m}} | ||
|- | |- | ||
− | + | | mile (geographical) (H) || <!--Please provide a reference for any symbols--> | |
| ≡ {{val|6082|u=ft}} | | ≡ {{val|6082|u=ft}} | ||
| = {{val|1853.7936|u=m}} | | = {{val|1853.7936|u=m}} | ||
|- | |- | ||
− | | | + | | mile (international) || mi |
| ≡ 80 chains ≡ {{val|5280|u=ft}} ≡ {{val|1760|u=yd}} | | ≡ 80 chains ≡ {{val|5280|u=ft}} ≡ {{val|1760|u=yd}} | ||
| ≡ {{val|1609.344|u=m}} | | ≡ {{val|1609.344|u=m}} | ||
|- | |- | ||
− | | | + | | mile (tactical or data) || |
| ≡ {{val|6000|u=ft}} | | ≡ {{val|6000|u=ft}} | ||
| ≡ {{val|1828.8|u=m}} | | ≡ {{val|1828.8|u=m}} | ||
Line 281: | Line 279: | ||
|- | |- | ||
| nail (cloth) || | | nail (cloth) || | ||
− | | ≡ {{frac|2|1|4}} in | + | | ≡ {{frac|2|1|4}} in |
| = {{val|0.05715|u=m}} | | = {{val|0.05715|u=m}} | ||
|- | |- | ||
− | | | + | | nanometre || nm |
| ≡ {{val|1|e=-9|u=m}} | | ≡ {{val|1|e=-9|u=m}} | ||
| ≡ {{val|1|e=-9|u=m}} | | ≡ {{val|1|e=-9|u=m}} | ||
|- | |- | ||
| nautical league || NL; nl | | nautical league || NL; nl | ||
− | | ≡ 3 nmi | + | | ≡ 3 nmi |
| = {{val|5556|u=m}} | | = {{val|5556|u=m}} | ||
|- | |- | ||
Line 296: | Line 294: | ||
| = {{val|1853.184|u=m}} | | = {{val|1853.184|u=m}} | ||
|- | |- | ||
− | | | + | | nautical mile (international) || NM; nmi |
− | | ≡ {{val|1852|u=m}} | + | | ≡ {{val|1852|u=m}} |
| ≡ {{val|1852|u=m}} | | ≡ {{val|1852|u=m}} | ||
|- | |- | ||
Line 305: | Line 303: | ||
|- | |- | ||
| pace || | | pace || | ||
− | | ≡ 2.5 ft | + | | ≡ 2.5 ft |
| = 0.762 m | | = 0.762 m | ||
|- | |- | ||
− | + | | palm || | |
− | | ≡ 3 in | + | | ≡ 3 in |
| = 0.0762 m | | = 0.0762 m | ||
|- | |- | ||
− | | | + | | parsec || pc |
− | | Distant point with a '''''par'''''allax shift of one arc '''''sec'''''ond from a base of one astronomical unit. <br />≡ {{sfrac|{{val|648000}}|{{pi}}}} | + | | Distant point with a '''''par'''''allax shift of one arc '''''sec'''''ond from a base of one astronomical unit. <br/>≡ {{sfrac|{{val|648000}}|{{pi}}}} au |
− | | ≈ {{val|30856775814913700|u=m}} | + | | ≈ {{val|30856775814913700|u=m}} |
|- | |- | ||
− | + | | pica || | |
| ≡ 12 points | | ≡ 12 points | ||
| Dependent on point measures. | | Dependent on point measures. | ||
|- | |- | ||
− | | | + | | picometre || pm |
| ≡ {{val|1|e=-12|u=m}} | | ≡ {{val|1|e=-12|u=m}} | ||
| ≡ {{val|1|e=-12|u=m}} | | ≡ {{val|1|e=-12|u=m}} | ||
|- | |- | ||
− | | | + | | point (American, English) || pt |
− | + | | ≡ {{frac|72.272}} in | |
− | | ≡ {{frac|72.272}} | ||
| ≈ {{val|0.000351450|u=m}} | | ≈ {{val|0.000351450|u=m}} | ||
|- | |- | ||
− | | point (Didot; European) | + | | point (Didot; European) || pt |
− | | ≡ {{frac|12}} × {{frac|72}} of | + | | ≡ {{frac|12}} × {{frac|72}} of pied du roi;<br /><br />After 1878:<br />≡ {{frac|5|133}} cm |
| ≈ {{val|0.00037597|u=m}};<br /><br />After 1878:<br />≈ {{val|0.00037593985|u=m}} | | ≈ {{val|0.00037597|u=m}};<br /><br />After 1878:<br />≈ {{val|0.00037593985|u=m}} | ||
|- | |- | ||
− | | point ( | + | | point (PostScript) || pt |
− | | ≡ {{frac|72}} | + | | ≡ {{frac|72}} in |
| = {{gaps|0.000|352{{overline|7}}}} m | | = {{gaps|0.000|352{{overline|7}}}} m | ||
|- | |- | ||
− | | point ( | + | | point (TeX) || pt |
− | | ≡ {{frac|72.27}} | + | | ≡ {{frac|72.27}} in |
| = 0.00{{overline|{{gaps|0|351|4598}}}} m | | = 0.00{{overline|{{gaps|0|351|4598}}}} m | ||
|- | |- | ||
Line 345: | Line 342: | ||
| = 0.2286 m | | = 0.2286 m | ||
|- | |- | ||
− | | | + | | rod; pole; perch (H) || rd |
| ≡ {{frac|16|1|2}} ft | | ≡ {{frac|16|1|2}} ft | ||
| = 5.0292 m | | = 5.0292 m | ||
|- | |- | ||
− | + | | rope (H) || rope | |
| ≡ 20 ft <ref name=CRC71/> | | ≡ 20 ft <ref name=CRC71/> | ||
| = 6.096 m | | = 6.096 m | ||
|- | |- | ||
− | + | | shaku (Japan) || | |
| ≡ 10/33 m | | ≡ 10/33 m | ||
| ≈ 0.303 0303 m | | ≈ 0.303 0303 m | ||
|- | |- | ||
| span (H) || | | span (H) || | ||
− | | ≡ 9 in | + | | ≡ 9 in |
| = 0.2286 m | | = 0.2286 m | ||
|- | |- | ||
− | | | + | | spat || |
| | | | ||
| ≡ {{val|1|e=12|u=m}} | | ≡ {{val|1|e=12|u=m}} | ||
Line 369: | Line 366: | ||
| = 0.0508 m | | = 0.0508 m | ||
|- | |- | ||
− | | | + | | toise (French, post 1667) (H) || T |
| ≡ 27000/13853 m | | ≡ 27000/13853 m | ||
| ≈ 1.949 0363 m | | ≈ 1.949 0363 m | ||
|- | |- | ||
− | | | + | | twip || twp |
| ≡ {{frac|1440}} in | | ≡ {{frac|1440}} in | ||
| = 1.763{{overline|8}}{{e|−5}} m | | = 1.763{{overline|8}}{{e|−5}} m | ||
|- | |- | ||
− | | | + | | x unit; siegbahn || xu |
| | | | ||
− | | ≈ {{val|1.0021|e=-13}} m | + | | ≈ {{val|1.0021|e=-13}} m |
|- | |- | ||
− | | | + | | yard (International) || yd |
− | | ≡ 0.9144 m | + | | ≡ 0.9144 m ≡ 3 ft ≡ 36 in |
| ≡ 0.9144 m | | ≡ 0.9144 m | ||
|- | |- | ||
− | | | + | | yoctometre || ym |
| ≡ {{val|1|e=-24|u=m}} | | ≡ {{val|1|e=-24|u=m}} | ||
| ≡ {{val|1|e=-24|u=m}} | | ≡ {{val|1|e=-24|u=m}} | ||
|- | |- | ||
− | | | + | | zeptometre || zm |
| ≡ {{val|1|e=-21|u=m}} | | ≡ {{val|1|e=-21|u=m}} | ||
| ≡ {{val|1|e=-21|u=m}} | | ≡ {{val|1|e=-21|u=m}} |
Revision as of 15:30, 16 December 2021
Conversion of units is the conversion between different units of measurement for the same quantity, typically through multiplicative conversion factors.
Contents
- 1 Techniques
- 2 Tables of conversion factors
- 2.1 Length
- 2.2 Area
- 2.3 Volume
- 2.4 Plane angle
- 2.5 Solid angle
- 2.6 Mass
- 2.7 Density
- 2.8 Time
- 2.9 Frequency
- 2.10 Speed or velocity
- 2.11 Flow (volume)
- 2.12 Acceleration
- 2.13 Force
- 2.14 Pressure or mechanical stress
- 2.15 Torque or moment of force
- 2.16 Energy
- 2.17 Power or heat flow rate
- 2.18 Action
- 2.19 Dynamic viscosity
- 2.20 Kinematic viscosity
- 2.21 Electric current
- 2.22 Electric charge
- 2.23 Electric dipole
- 2.24 Electromotive force, electric potential difference
- 2.25 Electrical resistance
- 2.26 Capacitance
- 2.27 Magnetic flux
- 2.28 Magnetic flux density
- 2.29 Inductance
- 2.30 Temperature
- 2.31 Information entropy
- 2.32 Luminous intensity
- 2.33 Luminance
- 2.34 Luminous flux
- 2.35 Illuminance
- 2.36 Radiation – source activity
- 2.37 Radiation – exposure
- 2.38 Radiation – absorbed dose
- 2.39 Radiation – equivalent dose
- 3 Licensing
Techniques
Process overview
The process of conversion depends on the specific situation and the intended purpose. This may be governed by regulation, contract, technical specifications or other published standards. Engineering judgment may include such factors as:
- The precision and accuracy of measurement and the associated uncertainty of measurement.
- The statistical confidence interval or tolerance interval of the initial measurement.
- The number of significant figures of the measurement.
- The intended use of the measurement including the engineering tolerances.
- Historical definitions of the units and their derivatives used in old measurements; e.g., international foot vs. US survey foot.
Some conversions from one system of units to another need to be exact, without increasing or decreasing the precision of the first measurement. This is sometimes called soft conversion. It does not involve changing the physical configuration of the item being measured.
By contrast, a hard conversion or an adaptive conversion may not be exactly equivalent. It changes the measurement to convenient and workable numbers and units in the new system. It sometimes involves a slightly different configuration, or size substitution, of the item. Nominal values are sometimes allowed and used.
Conversion factors
A conversion factor is used to change the units of a measured quantity without changing its value. The unity bracket method of unit conversion consists of a fraction in which the denominator is equal to the numerator, but they are in different units. Because of the identity property of multiplication, the value of a quantity will not change as long as it is multiplied by one. Also, if the numerator and denominator of a fraction are equal to each other, then the fraction is equal to one. So as long as the numerator and denominator of the fraction are equivalent, they will not affect the value of the measured quantity.
The following example demonstrates how the unity bracket method is used to convert the rate 5 kilometers per second to meters per second. The symbols km, m, and s represent kilometer, meter, and second, respectively.
Thus, it is found that 5 kilometers per second is equal to 5000 meters per second.
Software tools
There are many conversion tools. They are found in the function libraries of applications such as spreadsheets databases, in calculators, and in macro packages and plugins for many other applications such as the mathematical, scientific and technical applications.
There are many standalone applications that offer the thousands of the various units with conversions. For example, the free software movement offers a command line utility GNU units for Linux and Windows.
Calculation involving non-SI Units
In the cases where non-SI units are used, the numerical calculation of a formula can be done by first working out the pre-factor, and then plug in the numerical values of the given/known quantities.
For example, in the study of Bose–Einstein condensate, atomic mass m is usually given in daltons, instead of kilograms, and chemical potential μ is often given in Boltzmann constant times nanokelvin. The condensate's healing length is given by:
For a 23Na condensate with chemical potential of (Boltzmann constant times) 128 nK, the calculation of healing length (in micrometres) can be done in two steps:
Calculate the pre-factor
Assume that this gives
which is our pre-factor.
Calculate the numbers
Now, make use of the fact that . With , .
This method is especially useful for programming and/or making a worksheet, where input quantities are taking multiple different values; For example, with the pre-factor calculated above, it's very easy to see that the healing length of 174Yb with chemical potential 20.3 nK is .
Tables of conversion factors
This article gives lists of conversion factors for each of a number of physical quantities, which are listed in the index. For each physical quantity, a number of different units (some only of historical interest) are shown and expressed in terms of the corresponding SI unit. Conversions between units in the metric system are defined by their prefixes (for example, 1 kilogram = 1000 grams, 1 milligram = 0.001 grams) and are thus not listed in this article. Exceptions are made if the unit is commonly known by another name (for example, 1 micron = 10−6 metre). Within each table, the units are listed alphabetically, and the SI units (base or derived) are highlighted.
Symbol | Definition |
---|---|
≡ | exactly equal |
≈ | approximately equal to |
≘ | (exactly) corresponds to (different types of quantity describing the same phenomenon) |
indicates that digits repeat infinitely (e.g. corresponds to 8.294 369 369 369 369 ...) | |
(H) | of chiefly historical interest |
Length
Name of unit | Symbol | Definition | Relation to SI units |
---|---|---|---|
ångström | Å | ≡ 1 x 10-10 m | ≡ 0.1 nm |
astronomical unit | au | ≡ 149 597 870 700 m ≈ Distance from Earth to Sun |
≡ 149 597 870 700 m |
attometre | am | ≡ 1 x 10-18 m | ≡ 1 x 10-18 m |
barleycorn (H) | = in (see note above about rounding) | = m | |
bohr, atomic unit of length | a0 | = Bohr radius of hydrogen | (17) x 10-11 m |
cable length (imperial) | ≡ 608 ft | ≈ 185.3184 m | |
cable length (International) | ≡ nmi | ≡ 185.2 m | |
cable length (US) | ≡ 720 ft | = 219.456 m | |
chain (Gunter's; Surveyor's) | ch | ≡ 66 ft (US) ≡ 4 rods | ≈ 20.116 84 m |
cubit (H) | ≡ Distance from fingers to elbow ≈ 18 in | ≈ 0.5 m | |
ell (H) | ell | ≡ 45 in (In England usually) | = 1.143 m |
fathom | ftm | ≡ 6 ft | = 1.8288 m |
femtometre | fm | ≡ 1 x 10-15 m | ≡ 1 x 10-15 m |
fermi | fm | ≡ 1 x 10-15 m | ≡ 1 x 10-15 m |
finger | ≡ in | = 0.022 225 m | |
finger (cloth) | ≡ in | = 0.1143 m | |
foot (Benoît) (H) | ft (Ben) | ≈ 0.304 799 735 m | |
foot (Cape) (H) | Legally defined as 1.033 English feet in 1859 | ≈ 0.314 858 m | |
foot (Clarke's) (H) | ft (Cla) | ≈ 0.304 797 2654 m | |
foot (Indian) (H) | ft Ind | ≈ 0.304 799 514 m | |
foot, metric | mf | ≡ 300 mm | ≡ 0.3 m |
foot, metric (Mesures usuelles) (H) | ≡ m | ≡ m | |
foot (International) | ft | ≡ 0.3048 m ≡ yd ≡ 12 inches | ≡ 0.3048 m |
foot (Sear's) (H) | ft (Sear) | ≈ 0.304 799 47 m | |
foot (US Survey) | ft (US) | ≡ m | ≈ 0.304 800 610 m |
french; charriere | F | ≡ mm | = x 10-3 m |
furlong | fur | ≡ 10 chains = 660 ft = 220 yd | = 201.168 m |
hand | ≡ 4 in | ≡ 0.1016 m | |
inch (International) | in | ≡ 2.54 cm ≡ yd ≡ ft | ≡ 0.0254 m |
league (land) | lea | ≈ 1 hour walk, Currently defined in US as 3 Statute miles, but historically varied from 2 to 9 km | ≈ 4828 m |
light-day | ≡ 24 light-hours | ≡ 2.590 206 837 12 × 1013 m | |
light-hour | ≡ 60 light-minutes | ≡ 1.079 252 8488 × 1012 m | |
light-minute | ≡ 60 light-seconds | ≡ 1.798 754 748 × 1010 m | |
light-second | ≡ Distance light travels in one second in vacuum | ≡ 299 792 458 m | |
light-year | ly | ≡ Distance light travels in vacuum in 365.25 days | ≡ 9.460 730 472 5808 × 1015 m |
line | ln | ≡ in | = 0.002 11 m |
link (Gunter's; Surveyor's) | lnk | ≡ ch ≡ 0.66 ft (US) ≡ 7.92 in | ≈ 0.201 168 4 m |
link (Ramsden's; Engineer's) | lnk | ≡ 1 ft | = 0.3048 m |
metre (SI base unit) (meter) |
m | ≡ Distance light travels in of a second in vacuum. | (SI base unit) |
mickey | ≡ Template:Frac in | = Template:Val | |
micrometre (old: micron) | μ; μm | ≡ Template:Val | ≡ Template:Val |
mil; thou | mil | ≡ Template:Val | = Template:Val |
mil (Sweden and Norway) | mil | ≡ 10 km | = Template:Val |
mile (geographical) (H) | ≡ Template:Val | = Template:Val | |
mile (international) | mi | ≡ 80 chains ≡ Template:Val ≡ Template:Val | ≡ Template:Val |
mile (tactical or data) | ≡ Template:Val | ≡ Template:Val | |
mile (telegraph) (H) | mi | ≡ Template:Val | = Template:Val |
mile (US Survey) | mi | ≡ Template:Val US Survey feet ≡ (Template:Val × Template:Frac) m | ≈ Template:Val |
nail (cloth) | ≡ Template:Frac in | = Template:Val | |
nanometre | nm | ≡ Template:Val | ≡ Template:Val |
nautical league | NL; nl | ≡ 3 nmi | = Template:Val |
nautical mile (Admiralty) | NM (Adm); nmi (Adm) | = Template:Val | = Template:Val |
nautical mile (international) | NM; nmi | ≡ Template:Val | ≡ Template:Val |
nautical mile (US pre 1954) | ≡ 1853.248 m | ≡ 1853.248 m | |
pace | ≡ 2.5 ft | = 0.762 m | |
palm | ≡ 3 in | = 0.0762 m | |
parsec | pc | Distant point with a parallax shift of one arc second from a base of one astronomical unit. ≡ Template:Sfrac au |
≈ Template:Val |
pica | ≡ 12 points | Dependent on point measures. | |
picometre | pm | ≡ Template:Val | ≡ Template:Val |
point (American, English) | pt | ≡ Template:Frac in | ≈ Template:Val |
point (Didot; European) | pt | ≡ Template:Frac × Template:Frac of pied du roi; After 1878: ≡ Template:Frac cm |
≈ Template:Val; After 1878: ≈ Template:Val |
point (PostScript) | pt | ≡ Template:Frac in | = Template:Gaps m |
point (TeX) | pt | ≡ Template:Frac in | = 0.00Template:Overline m |
quarter | ≡ Template:Frac yd | = 0.2286 m | |
rod; pole; perch (H) | rd | ≡ Template:Frac ft | = 5.0292 m |
rope (H) | rope | ≡ 20 ft [1] | = 6.096 m |
shaku (Japan) | ≡ 10/33 m | ≈ 0.303 0303 m | |
span (H) | ≡ 9 in | = 0.2286 m | |
spat | ≡ Template:Val | ||
stick (H) | ≡ 2 in | = 0.0508 m | |
toise (French, post 1667) (H) | T | ≡ 27000/13853 m | ≈ 1.949 0363 m |
twip | twp | ≡ Template:Frac in | = 1.763Template:OverlineTemplate:E m |
x unit; siegbahn | xu | ≈ Template:Val m | |
yard (International) | yd | ≡ 0.9144 m ≡ 3 ft ≡ 36 in | ≡ 0.9144 m |
yoctometre | ym | ≡ Template:Val | ≡ Template:Val |
zeptometre | zm | ≡ Template:Val | ≡ Template:Val |
Area
Name of unit | Symbol | Definition | Relation to SI units |
---|---|---|---|
acre (international) | ac | ≡ Template:Nowrap = Template:Val | ≡ Template:Val |
acre (US survey) | ac | ≡ 10 sq ch = Template:Val, also Template:Val | ≈ Template:Val[2] |
are | a | ≡ 100 m2 | ≡ 100 m2 |
barn | b | ≡ 10−28 m2 | ≡ 10−28 m2 |
barony | ≡ Template:Val ac | ≡ Template:Val | |
board | bd | ≡ Template:Nowrap | ≡ Template:Val |
boiler horsepower equivalent direct radiation | bhp EDR | ≡ 1 ft2 × 1 bhp / (240 BTUIT/h) | ≈ Template:Val |
circular inch | circ in | ≡ Template:Frac sq in | ≈ Template:Val |
circular mil; circular thou | circ mil | ≡ Template:Frac mil2 | ≈ Template:Val |
cord | ≡ 192 bd | ≡ Template:Val | |
cuerda (PR Survey) | cda | ≡ 1 cda x 1 cda = Template:Val acre | ≡ Template:Val |
dunam | ≡ Template:Val | ≡ Template:Val | |
guntha (India) | ≡ 121 sq yd | ≈ 101.17 m2 | |
hectare | ha | ≡ Template:Val | ≡ Template:Val |
hide | ≈ 120 ac (variable) | ≈ Template:Val | |
rood | ro | ≡ Template:Frac ac | = Template:Val |
ping | ≡ Template:Frac m × Template:Frac m | ≈ Template:Val | |
section | ≡ Template:Nowrap | = Template:Val | |
shed | ≡ 10−52 m2 | = 10−52 m2 | |
square (roofing) | ≡ Template:Nowrap | = Template:Val | |
square chain (international) | sq ch | ≡ Template:Nowrap = Template:Frac ac | ≡ Template:Val |
square chain (US Survey) | sq ch | ≡ Template:Nowrap = Template:Frac US survey acre | ≈ Template:Val |
square foot | sq ft | ≡ Template:Nowrap | ≡ Template:Val |
square foot (US Survey) | sq ft | ≡ Template:Nowrap | ≈ Template:Val |
square inch | sq in | ≡ Template:Nowrap | ≡ Template:Val |
square kilometre | km2 | ≡ 1 km × 1 km | = 106 m2 |
square link (Gunter's)(International) | sq lnk | ≡ 1 lnk × 1 lnk ≡ 0.66 ft × 0.66 ft | = Template:Val |
square link (Gunter's)(US Survey) | sq lnk | ≡ Template:Nowrap ≡ Template:Nowrap | ≈ Template:Val |
square link (Ramsden's) | sq lnk | ≡ 1 lnk × 1 lnk ≡ 1 ft × 1 ft | = Template:Val |
square metre (SI unit) | m2 | ≡ 1 m × 1 m | = 1 m2 |
square mil; square thou | sq mil | ≡ 1 mil × 1 mil | = Template:Val |
square mile | sq mi | ≡ 1 mi × 1 mi | ≡ Template:Val |
square mile (US Survey) | sq mi | ≡ 1 mi (US) × 1 mi (US) | ≈ Template:Val |
square rod/pole/perch | sq rd | ≡ 1 rd × 1 rd | = Template:Val |
square yard (International) | sq yd | ≡ 1 yd × 1 yd | ≡ Template:Val |
stremma | ≡ Template:Val | = Template:Val | |
township | ≡ 36 sq mi (US) | ≈ Template:Val | |
yardland | ≈ 30 ac | ≈ Template:Val |
Volume
Name of unit | Symbol | Definition | Relation to SI units |
---|---|---|---|
acre-foot | ac ft | ≡ 1 ac x 1 ft = Template:Val | = Template:Val |
acre-inch | ≡ 1 ac × 1 in | = Template:Val | |
barrel (imperial) | bl (imp) | ≡ 36 gal (imp) | = Template:Val |
barrel (petroleum); archaic blue-barrel | bl; bbl | ≡ 42 gal (US) | = Template:Val |
barrel (US dry) | bl (US) | ≡ 105 qt (US) = 105/32 bu (US lvl) | = Template:Val |
barrel (US fluid) | fl bl (US) | ≡ Template:Frac gal (US) | = Template:Val |
board-foot | bdft | ≡ 144 cu in | ≡ Template:Val |
bucket (imperial) | bkt | ≡ 4 gal (imp) | = Template:Val |
bushel (imperial) | bu (imp) | ≡ 8 gal (imp) | = Template:Val |
bushel (US dry heaped) | bu (US) | ≡ Template:Frac bu (US lvl) | = Template:Val |
bushel (US dry level) | bu (US lvl) | ≡ Template:Val | = Template:Val |
butt, pipe | ≡ 126 gal (US) (wine) | = Template:Val | |
coomb | ≡ 4 bu (imp) | = Template:Val | |
cord (firewood) | ≡ Template:Nowrap | = Template:Val | |
cord-foot | ≡ 16 cu ft | = Template:Val | |
cubic fathom | cu fm | ≡ 1 fm × 1 fm × 1 fm | = Template:Val |
cubic foot | ft3 | ≡ 1 ft × 1 ft × 1 ft | ≡ Template:Val |
cubic inch | in3 | ≡ 1 in × 1 in × 1 in | ≡ Template:Val |
cubic metre (SI unit) | m3 | ≡ 1 m × 1 m × 1 m | ≡ 1 m3 |
cubic mile | cu mi | ≡ 1 mi × 1 mi × 1 mi | ≡ Template:Val |
cubic yard | yd3 | ≡ 27 cu ft | ≡ Template:Val |
cup (breakfast) | ≡ 10 fl oz (imp) | = Template:Val | |
cup (Canadian) | c (CA) | ≡ 8 fl oz (imp) | = Template:Val |
cup (metric) | c | ≡ Template:Val | ≡ Template:Val |
cup (US customary) | c (US) | ≡ 8 US fl oz ≡ Template:Frac gal (US) | = Template:Val |
cup (US food nutrition labeling) | c (US) | ≡ 240 mL[3] | = Template:Val |
dash (imperial) | ≡ Template:Frac gi (imp) = Template:Frac pinch (imp) | = Template:GapsTemplate:E m3 | |
dash (US) | ≡ Template:Frac US fl oz = Template:Frac US pinch | = Template:Val | |
dessertspoon (imperial) | ≡ Template:Frac gi (imp) | = Template:GapsTemplate:E m3 | |
drop (imperial) | gtt | ≡ Template:Frac fl oz (imp) | = Template:GapsTemplate:E m3 |
drop (imperial) (alt) | gtt | ≡ Template:Frac gi (imp) | ≈ Template:Val |
drop (medical) | ≡ Template:Frac mL | = 83.Template:OverlineTemplate:E m3 | |
drop (metric) | ≡ Template:Frac mL | = Template:Val | |
drop (US) | gtt | ≡ Template:Frac US fl oz | = Template:GapsTemplate:E m3 |
drop (US) (alt) | gtt | ≡ Template:Frac US fl oz | ≈ Template:Val |
drop (US) (alt) | gtt | ≡ Template:Frac US fl oz | ≈ Template:Val |
fifth | ≡ Template:Frac US gal | = Template:Val | |
firkin | ≡ 9 gal (imp) | = Template:Val | |
fluid drachm (imperial) | fl dr | ≡ Template:Frac fl oz (imp) | = Template:Val |
fluid dram (US); US fluidram | fl dr | ≡ Template:Frac US fl oz | = Template:Val |
fluid scruple (imperial) | fl s | ≡ Template:Frac fl oz (imp) | = Template:GapsTemplate:E m3 |
gallon (beer) | beer gal | ≡ 282 cu in | = Template:Val |
gallon (imperial) | gal (imp) | ≡ Template:Val | ≡ Template:Val |
gallon (US dry) | gal (US) | ≡ Template:Frac bu (US lvl) | = Template:Val |
gallon (US fluid; Wine) | gal (US) | ≡ 231 cu in | ≡ Template:Val |
gill (imperial); Noggin | gi (imp); nog | ≡ 5 fl oz (imp) | = Template:Val |
gill (US) | gi (US) | ≡ 4 US fl oz | = Template:Val |
hogshead (imperial) | hhd (imp) | ≡ 2 bl (imp) | = Template:Val |
hogshead (US) | hhd (US) | ≡ 2 fl bl (US) | = Template:Val |
jigger (bartending) | ≡ Template:Frac US fl oz | ≈ Template:Val | |
kilderkin | ≡ 18 gal (imp) | = Template:Val | |
lambda | λ | ≡ 1 mm3 | = Template:Val |
last | ≡ 80 bu (imp) | = Template:Val | |
litre (liter) |
L or l | ≡ 1 dm3 [4] | ≡ 0.001 m3 |
load | ≡ 50 cu ft | = Template:Val | |
minim (imperial) | min | ≡ Template:Frac fl oz (imp) = 1/60 fl dr (imp) | = Template:GapsTemplate:E m3 |
minim (US) | min | ≡ Template:Frac US fl oz = Template:Frac US fl dr | = Template:Val |
ounce (fluid imperial) | fl oz (imp) | ≡ Template:Frac gal (imp) | ≡ Template:Val |
ounce (fluid US customary) | US fl oz | ≡ Template:Frac gal (US) | ≡ Template:Val |
ounce (fluid US food nutrition labeling) | US fl oz | ≡ 30 mL[3] | ≡ Template:Val |
peck (imperial) | pk | ≡ 2 gal (imp) | = Template:Val |
peck (US dry) | pk | ≡ Template:Frac US lvl bu | = Template:Val |
perch | per | ≡ Template:Nowrap | = Template:Val |
pinch (imperial) | ≡ Template:Frac gi (imp) = 1/16 tsp (imp) | = Template:GapsTemplate:E m3 | |
pinch (US) | ≡ Template:Frac US fl oz = 1/16 US tsp | = Template:Val | |
pint (imperial) | pt (imp) | ≡ Template:Frac gal (imp) | = Template:Val |
pint (US dry) | pt (US dry) | ≡ Template:Frac bu (US lvl) ≡ Template:Frac gal (US dry) | = Template:Val |
pint (US fluid) | pt (US fl) | ≡ Template:Frac gal (US) | = Template:Val |
pony | ≡ Template:Frac US fl oz | = Template:Val | |
pottle; quartern | ≡ Template:Frac gal (imp) = 80 fl oz (imp) | = Template:Val | |
quart (imperial) | qt (imp) | ≡ Template:Frac gal (imp) | = Template:Val |
quart (US dry) | qt (US) | ≡ Template:Frac bu (US lvl) = Template:Frac gal (US dry) | = Template:Val |
quart (US fluid) | qt (US) | ≡ Template:Frac gal (US fl) | = Template:Val |
quarter; pail | ≡ 8 bu (imp) | = Template:Val | |
register ton | ≡ 100 cu ft | = Template:Val | |
sack (US) | ≡ 3 bu (US lvl) | = Template:Val | |
seam | ≡ 8 bu [5] | = Template:Val | |
shot (US) | usually 1.5 US fl oz[5] | ≈ Template:Val | |
strike (imperial) | ≡ 2 bu (imp) | = Template:Val | |
strike (US) | ≡ 2 bu (US lvl) | = Template:Val | |
tablespoon (Australian metric) | ≡ Template:Val | ||
tablespoon (Canadian) | tbsp | ≡ Template:Frac fl oz (imp) | = Template:Val |
tablespoon (imperial) | tbsp | ≡ Template:Frac fl oz (imp) | = Template:Val |
tablespoon (metric) | ≡ Template:Val | ||
tablespoon (US customary) | tbsp | ≡ Template:Frac US fl oz | = Template:Val |
tablespoon (US food nutrition labeling) | tbsp | ≡ 15 mL[3] | = Template:Val |
teaspoon (Canadian) | tsp | ≡ Template:Frac fl oz (imp) | = Template:GapsTemplate:E m3 |
teaspoon (imperial) | tsp | ≡ Template:Frac gi (imp) | = Template:GapsTemplate:E m3 |
teaspoon (metric) | ≡ Template:Val | ≡ Template:Val | |
teaspoon (US customary) | tsp | ≡ Template:Frac US fl oz | = Template:Val |
teaspoon (US food nutrition labeling) | tsp | ≡ 5 mL[3] | = Template:Val |
timber foot | ≡ 1 cu ft | = Template:Val | |
ton (displacement) | ≡ 35 cu ft | = Template:Val | |
ton (freight) | ≡ 40 cu ft | = Template:Val | |
ton (water) | ≡ 28 bu (imp) | = Template:Val | |
tun | ≡ 252 gal (wine) | = Template:Val | |
wey (US) | ≡ 40 bu (US lvl) | = Template:Val |
Plane angle
Name of unit | Symbol | Definition | Relation to SI units |
---|---|---|---|
NATO mil | (various) | ≡ Template:Frac rad | ≈ Template:Val |
Swedish streck | ≡ Template:Frac rad | ≈ Template:Val | |
milliradian | mrad | ≡ Template:Frac rad | ≈ Template:Val |
Warsaw Pact mil | ≡ Template:Frac rad | ≈ Template:Val | |
arcminute; MOA | ' | ≡ Template:Frac | ≈ Template:Val |
arcsecond | " | ≡ Template:Frac | ≈ Template:Val |
centesimal minute of arc | ' | ≡ Template:Frac grad | ≈ Template:Val |
centesimal second of arc | " | ≡ Template:Frac grad | ≈ Template:Val |
degree (of arc) | ° | ≡ Template:Frac of a revolution ≡ Template:Frac rad | ≈ Template:Val |
grad; gradian; gon | grad | ≡ Template:Frac of a revolution ≡ Template:Frac rad ≡ 0.9° | Template:Nowrap |
octant | ≡ 45° | ≈ Template:Val | |
quadrant | ≡ 90° | ≈ Template:Val | |
radian (SI unit) | rad | The angle subtended at the center of a circle by an arc whose length is equal to the circle's radius. One full revolution encompasses 2π radians. |
= 1 rad |
sextant | ≡ 60° | ≈ Template:Val | |
sign | ≡ 30° | ≈ Template:Val |
Solid angle
Name of unit | Symbol | Definition | Relation to SI units |
---|---|---|---|
spat | Template:Nowrap[5] – The solid angle subtended by a sphere at its centre. | Template:Nowrap | |
square degree | deg2; sq.deg.; (°)2 | Template:Nowrap | Template:Nowrap |
steradian (SI unit) | sr | The solid angle subtended at the center of a sphere of radius r by a portion of the surface of the sphere having an area r2. A sphere subtends 4π sr.[5] |
= 1 sr |
Mass
Notes:
- See Weight for detail of mass/weight distinction and conversion.
- Avoirdupois is a system of mass based on a pound of 16 ounces, while Troy weight is the system of mass where 12 troy ounces equals one troy pound.
- In this table, the symbol g0 is used to denote standard gravity in order to avoid confusion with the (upright) g symbol for gram.
Name of unit | Symbol | Definition | Relation to SI units |
---|---|---|---|
atomic mass unit, unified | u; AMU | Same as dalton (see below) | ≈ Template:Val[6] |
atomic unit of mass, electron rest mass | me | ≈ Template:Val[7] | |
bag (coffee) | ≡ 60 kg | = 60 kg | |
bag (Portland cement) | ≡ 94 lb av | = Template:Val | |
barge | ≡ Template:Frac short ton | = Template:Val | |
carat | kt | ≡ Template:Frac gr | = Template:ValTemplate:Overline mg |
carat (metric) | ct | ≡ 200 mg | = 200 mg |
clove | ≡ 8 lb av | = Template:Val | |
crith | ≡ mass of 1 L of hydrogen gas at STP | ≈ 89.9349 mg | |
dalton | Da | 1/12 the mass of an unbound neutral atom of carbon-12 in its nuclear and electronic ground state and at rest | ≈ Template:Val[6] |
dram (apothecary; troy) | dr t | ≡ 60 gr | = Template:Val |
dram (avoirdupois) | dr av | ≡ Template:Frac gr | = Template:Val |
electronvolt | eV | ≡ 1 eV (energy unit) / c2 | = Template:Val[6] |
gamma | γ | ≡ 1 μg | = 1 μg |
grain | gr | ≡ Template:Frac lb av | ≡ Template:Val |
grave | gv | grave was the original name of the kilogram | ≡ 1 kg |
hundredweight (long) | long cwt or cwt | ≡ 112 lb av | = Template:Val |
hundredweight (short); cental | sh cwt | ≡ 100 lb av | = Template:Val |
kilogram (kilogramme) |
kg | ≈ mass of the prototype near Paris ≈ mass of 1 litre of water |
(SI base unit)[8] |
kip | kip | ≡ Template:Val av | = Template:Val |
mark | ≡ 8 oz t | = Template:Val | |
mite | ≡ Template:Frac gr | = Template:Val | |
mite (metric) | ≡ Template:Frac g | = 50 mg | |
ounce (apothecary; troy) | oz t | ≡ Template:Frac lb t | = Template:Val |
ounce (avoirdupois) | oz av | ≡ Template:Frac lb | = Template:Val |
ounce (US food nutrition labelling) | oz | ≡ 28 g[3] | = 28 g |
pennyweight | dwt; pwt | ≡ Template:Frac oz t | = Template:Val |
point | ≡ Template:Frac ct | = 2 mg | |
pound (avoirdupois) | lb av | ≡ Template:Val = Template:Val grains | ≡ Template:Val |
pound (metric) | ≡ 500 g | = 500 g | |
pound (troy) | lb t | ≡ Template:Val grains | = Template:Val |
quarter (imperial) | ≡ Template:Frac long cwt = 2 st = 28 lb av | = Template:Val | |
quarter (informal) | ≡ Template:Frac short ton | = Template:Val | |
quarter, long (informal) | ≡ Template:Frac long ton | = Template:Val | |
quintal (metric) | q | ≡ 100 kg | = 100 kg |
scruple (apothecary) | s ap | ≡ 20 gr | = Template:Val |
sheet | ≡ Template:Frac lb av | = 647.9891 mg | |
slug; geepound; hyl | slug | ≡ g0 × 1 lb av × 1 s2/ft | ≈ Template:Val |
stone | st | ≡ 14 lb av | = Template:Val |
ton, assay (long) | AT | ≡ 1 mg × 1 long ton ÷ 1 oz t | = 32.Template:Overline g |
ton, assay (short) | AT | ≡ 1 mg × 1 short ton ÷ 1 oz t | = 29.1Template:Overline g |
ton, long | long tn or ton | ≡ Template:Val | = Template:Val |
ton, short | sh tn | ≡ Template:Val | = Template:Val |
tonne (mts unit) | t | ≡ Template:Val | = Template:Val |
wey | ≡ 252 lb = 18 st | = Template:Val (variants exist) | |
Zentner | Ztr. | Definitions vary.[5][9] |
Density
Name of unit | Symbol | Definition | Relation to SI units |
---|---|---|---|
gram per millilitre | g/mL | ≡ g/mL | = Template:Val |
kilogram per cubic metre (SI unit) | kg/m3 | ≡ kg/m3 | = 1 kg/m3 |
kilogram per litre | kg/L | ≡ kg/L | = Template:Val |
ounce (avoirdupois) per cubic foot | oz/ft3 | ≡ oz/ft3 | ≈ Template:Val |
ounce (avoirdupois) per cubic inch | oz/in3 | ≡ oz/in3 | ≈ Template:Val |
ounce (avoirdupois) per gallon (imperial) | oz/gal | ≡ oz/gal | ≈ Template:Val |
ounce (avoirdupois) per gallon (US fluid) | oz/gal | ≡ oz/gal | ≈ Template:Val |
pound (avoirdupois) per cubic foot | lb/ft3 | ≡ lb/ft3 | ≈ Template:Val |
pound (avoirdupois) per cubic inch | lb/in3 | ≡ lb/in3 | ≈ Template:Val |
pound (avoirdupois) per gallon (imperial) | lb/gal | ≡ lb/gal | ≈ Template:Val |
pound (avoirdupois) per gallon (US fluid) | lb/gal | ≡ lb/gal | ≈ Template:Val |
slug per cubic foot | slug/ft3 | ≡ slug/ft3 | ≈ Template:Val |
Time
Name of unit | Symbol | Definition | Relation to SI units |
---|---|---|---|
Atomic unit of time | au | ≡ a0/(α⋅c) | ≈ Template:Val |
Callippic cycle | ≡ 441 mo (hollow) + 499 mo (full) = 76 a of 365.25 d | = Template:Val or Template:Val[note 1] | |
Century | c | ≡ 100 years (100 a) | = Template:Val[note 2][note 3] |
Day | d | = 24 h = Template:Val min | = Template:Val[note 3] |
Day (sidereal) | d | ≡ Time needed for the Earth to rotate once around its axis, determined from successive transits of a very distant astronomical object across an observer's meridian (International Celestial Reference Frame) | ≈ Template:Val |
Decade | dec | ≡ 10 years (10 a) | = Template:Val[note 2][note 3] |
Fortnight | fn | ≡ 2 wk | = Template:Val[note 3] |
Helek | ≡ Template:Frac h | = 3.Template:Overline s | |
Hipparchic cycle | ≡ 4 Callippic cycles - 1 d | = Template:Val | |
Hour | h | ≡ 60 min | = Template:Val[note 3] |
Jiffy | j | ≡ Template:Frac s | = 16.Template:Overline ms |
Jiffy (alternative) | ja | ≡ Template:Frac s | = 10 ms |
Ke (quarter of an hour) | ≡ Template:Frac h = Template:Frac d = 15 min | = 900 s | |
Ke (traditional) | ≡ Template:Frac d = 14.4 min | = 864 s | |
Lustre; Lustrum | ≡ 5 a of 365 d[note 4] | = Template:Val | |
Metonic cycle; enneadecaeteris | ≡ 110 mo (hollow) + 125 mo (full) = 6940 d ≈ 19 a | = Template:Val | |
Millennium | ≡ Template:Val years (Template:Val) | = Template:Val[note 2][note 3] | |
Milliday | md | ≡ Template:Frac d | = 86.4 s |
Minute | min | ≡ 60 s, due to leap seconds sometimes 59 s or 61 s, | = 60 s[note 3] |
Moment | ≡ 90 s | = 90 s | |
Month (full) | mo | ≡ 30 d[10] | = Template:Val[note 3] |
Month (Greg. av.) | mo | = Template:Val | ≈ Template:Val[note 3] |
Month (hollow) | mo | ≡ 29 d[10] | = Template:Val[note 3] |
Month (synodic) | mo | Cycle time of moon phases ≈ Template:Val (average) | ≈ Template:Val |
Octaeteris | = 48 mo (full) + 48 mo (hollow) + 3 mo (full)[11][12] = 8 a of 365.25 d = 2922 d | = Template:Val[note 3] | |
Planck time | ≡ (Template:Frac)Template:Frac | ≈ Template:Val[13] | |
Second (SI base unit) | s | ≡ Time of Template:Val periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom at 0 K[8] (but other seconds are sometimes used in astronomy). Also that time it takes for light to travel a distance of Template:Val metres. | (SI base unit) |
Shake | ≡ 10−8 s | = 10 ns | |
Sigma | ≡ 10−6 s | = 1 μs | |
Sothic cycle | ≡ Template:Val a of 365 d | = Template:Val | |
Svedberg | S | ≡ 10−13 s | = 100 fs |
Week | wk | ≡ 7 d = 168 h = Template:Val | = Template:Val[note 3] |
Year (common) | Template:Nowrap | 365 d | = Template:Val[note 3][14] |
Year (Gregorian) | a, y, or yr | = 365.2425 d average, calculated from common years (365 d) plus leap years (366 d) on most years divisible by 4. See leap year for details. | = Template:Val[note 3] |
Year (Julian) | a, y, or yr | = 365.25 d average, calculated from common years (365 d) plus one leap year (366 d) every four years | = Template:Val |
Year (leap) | a, y, or yr | 366 d | = Template:Val[note 3][14] |
Year (mean tropical) | a, y, or yr | Conceptually, the length of time it takes for the Sun to return to the same position in the cycle of seasons, [Converter 1] approximately Template:Val d, each day being Template:Val SI seconds[15] | ≈ Template:Val |
Year (sidereal) | a, y, or yr | ≡ Time taken for Sun to return to the same position with respect to the stars of the celestial sphere, approximately Template:Val | ≈ Template:Val |
Notes:
|
Frequency
Name of unit | Symbol | Definition | Relation to SI units |
---|---|---|---|
Actions per minute | APM | ≡ 1/60 Hz | ≈ Template:Val |
Cycle per second | cps | ≡ 1 Hz | = 1 cps = 1 Hz |
degree per second | deg/s | ≡ 1 °/s ≡ 1/360 Hz | = Template:ValTemplate:Overline Hz |
hertz (SI unit) | Hz | ≡ One cycle per second | = 1 Hz = 1/s |
Radian per second | rad/s | ≡ 1/(2π) Hz | ≈ Template:Val |
revolutions per minute | rpm | ≡ One unit rpm equals one rotation completed around a fixed axis in one minute of time. | ≈ Template:Val |
Speed or velocity
Name of unit | Symbol | Definition | Relation to SI units |
---|---|---|---|
foot per hour | fph | ≡ 1 ft/h | = 8.4Template:OverlineTemplate:E m/s |
foot per minute | fpm | ≡ 1 ft/min | = Template:Val |
foot per second | fps | ≡ 1 ft/s | = Template:Val |
furlong per fortnight | ≡ furlong/fortnight | ≈ Template:Val | |
inch per hour | iph | ≡ 1 in/h | = 7.0Template:OverlineTemplate:E m/s |
inch per minute | ipm | ≡ 1 in/min | = 4.2Template:OverlineTemplate:E m/s |
inch per second | ips | ≡ 1 in/s | = Template:Val |
kilometre per hour | km/h | ≡ 1 km/h | = 2.Template:OverlineTemplate:E m/s |
knot | kn | ≡ 1 nmi/h = 1.852 km/h | = 0.51Template:Overline m/s |
knot (Admiralty) | kn | ≡ 1 NM (Adm)/h = Template:Val[16] | = Template:ValTemplate:Overline m/s |
mach number | M | Ratio of the speed to the speed of sound[note 1] in the medium (unitless). | ≈ 340 m/s in air at sea level ≈ 295 m/s in air at jet altitudes |
metre per second (SI unit) | m/s | ≡ 1 m/s | = 1 m/s |
mile per hour | mph | ≡ 1 mi/h | = Template:Val |
mile per minute | mpm | ≡ 1 mi/min | = Template:Val |
mile per second | mps | ≡ 1 mi/s | = Template:Val |
speed of light in vacuum | c | ≡ Template:Val | = Template:Val |
speed of sound in air | s | Template:Val to Template:Val (Template:Convert)[note 1] | ≈ Template:Val |
|
A velocity consists of a speed combined with a direction; the speed part of the velocity takes units of speed.
Flow (volume)
Name of unit | Symbol | Definition | Relation to SI units |
---|---|---|---|
cubic foot per minute | CFMTemplate:Citation needed | ≡ 1 ft3/min | = Template:Val |
cubic foot per second | ft3/s | ≡ 1 ft3/s | = Template:Val |
cubic inch per minute | in3/min | ≡ 1 in3/min | = Template:ValTemplate:OverlineTemplate:E m3/s |
cubic inch per second | in3/s | ≡ 1 in3/s | = Template:Val |
cubic metre per second (SI unit) | m3/s | ≡ 1 m3/s | = 1 m3/s |
gallon (US fluid) per day | GPDTemplate:Citation needed | ≡ 1 gal/d | = Template:ValTemplate:OverlineTemplate:E m3/s |
gallon (US fluid) per hour | GPHTemplate:Citation needed | ≡ 1 gal/h | = Template:ValTemplate:OverlineTemplate:E m3/s |
gallon (US fluid) per minute | GPMTemplate:Citation needed | ≡ 1 gal/min | = Template:Val |
litre per minute | l/min or L/min | ≡ 1 L/min | = 1.Template:OverlineTemplate:E m3/s |
Acceleration
Name of unit | Symbol | Definition | Relation to SI units |
---|---|---|---|
foot per hour per second | fph/s | ≡ 1 ft/(h⋅s) | = 8.4Template:OverlineTemplate:E m/s2 |
foot per minute per second | fpm/s | ≡ 1 ft/(min⋅s) | = Template:Val |
foot per second squared | fps2 | ≡ 1 ft/s2 | = Template:Val |
gal; galileo | Gal | ≡ 1 cm/s2 | = 10−2 m/s2 |
inch per minute per second | ipm/s | ≡ 1 in/(min⋅s) | = 4.2Template:OverlineTemplate:E m/s2 |
inch per second squared | ips2 | ≡ 1 in/s2 | = Template:Val |
knot per second | kn/s | ≡ 1 kn/s | ≈ 5.1Template:OverlineTemplate:E m/s2 |
metre per second squared (SI unit) | m/s2 | ≡ 1 m/s2 | = 1 m/s2 |
mile per hour per second | mph/s | ≡ 1 mi/(h⋅s) | = Template:Val |
mile per minute per second | mpm/s | ≡ 1 mi/(min⋅s) | = 26.8224 m/s2 |
mile per second squared | mps2 | ≡ 1 mi/s2 | = Template:Val |
standard gravity | g0 | ≡ Template:Val | = Template:Val |
Force
Name of unit | Symbol | Definition | Relation to SI units |
---|---|---|---|
atomic unit of force | ≡ Template:Frac | ≈ Template:Val[18] | |
dyne (CGS unit) | dyn | ≡ g⋅cm/s2 | = 10−5 N |
kilogram-force; kilopond; grave-force | kgf; kp; gvf | ≡ g0 × 1 kg | = Template:Val |
kip; kip-force | kip; kipf; klbf | ≡ g0 × Template:Val | = Template:Val |
milligrave-force, gravet-force | mgvf; gvtf | ≡ g0 × 1 g | = Template:Val |
long ton-force | tnfTemplate:Citation needed | ≡ g0 × 1 long ton | = Template:Val |
newton (SI unit) | N | A force capable of giving a mass of one kilogram an acceleration of one metre per second per second.[19] | = 1 N = 1 kg⋅m/s2 |
ounce-force | ozf | ≡ g0 × 1 oz | = Template:Val |
pound-force | lbf | ≡ g0 × 1 lb | = Template:Val |
poundal | pdl | ≡ 1 lb⋅ft/s2 | = Template:Val |
short ton-force | tnfTemplate:Citation needed | ≡ g0 × 1 short ton | = Template:Val |
sthene (mts unit) | sn | ≡ 1 t⋅m/s2 | = 103 N |
Pressure or mechanical stress
Name of unit | Symbol | Definition | Relation to SI units |
---|---|---|---|
atmosphere (standard) | atm | ≡ Template:Val[20] | |
atmosphere (technical) | at | ≡ 1 kgf/cm2 | = Template:Val[20] |
bar | bar | ≡ Template:Val Pa | ≡ 105 Pa |
barye (CGS unit) | ≡ 1 dyn/cm2 | = 0.1 Pa | |
centimetre of mercury | cmHg | ≡ Template:Val × 1 cm × g0 | ≈ Template:Val[20] |
centimetre of water (4 °C) | cmH2O | ≈ 999.972 kg/m3 × 1 cm × g0 | ≈ Template:Val[20] |
foot of mercury (conventional) | ftHg | ≡ Template:Val × 1 ft × g0 | ≈ Template:Val[20] |
foot of water (39.2 °F) | ftH2O | ≈ 999.972 kg/m3 × 1 ft × g0 | ≈ Template:Val[20] |
inch of mercury (conventional) | inHg | ≡ Template:Val × 1 in × g0 | ≈ Template:Val[20] |
inch of water (39.2 °F) | inH2O | ≈ 999.972 kg/m3 × 1 in × g0 | ≈ Template:Val[20] |
kilogram-force per square millimetre | kgf/mm2 | ≡ 1 kgf/mm2 | = Template:Val[20] |
kip per square inch | ksi | ≡ 1 kipf/sq in | ≈ Template:Val[20] |
long ton per square foot | ≡ 1 long ton × g0 / 1 sq ft | ≈ Template:Val | |
micrometre of mercury | μmHg | ≡ Template:Val × 1 μm × g0 ≈ 0.001 torr | ≈ Template:Val[20] |
millimetre of mercury | mmHg | ≡ Template:Val × 1 mm × g0 ≈ 1 torr | ≈ Template:Val[20] |
millimetre of water (3.98 °C) | mmH2O | ≈ 999.972 kg/m3 × 1 mm × g0 = Template:Val | = Template:Val |
pascal (SI unit) | Pa | ≡ N/m2 = kg/(m⋅s2) | = 1 Pa[21] |
pièze (mts unit) | pz | ≡ Template:Val | = Template:Val = 1 kPa |
pound per square foot | psf | ≡ 1 lbf/ft2 | ≈ Template:Val[20] |
pound per square inch | psi | ≡ 1 lbf/in2 | ≈ Template:Val[20] |
poundal per square foot | pdl/sq ft | ≡ 1 pdl/sq ft | ≈ Template:Val[20] |
short ton per square foot | ≡ 1 short ton × g0 / 1 sq ft | ≈ Template:Val | |
torr | torr | ≡ Template:Frac Pa | ≈ Template:Val[20] |
Torque or moment of force
Name of unit | Symbol | Definition | Relation to SI units |
---|---|---|---|
pound-force-foot | lbf⋅ft | ≡ g0 × 1 lb × 1 ft | = Template:Val |
poundal-ft | pdl⋅ft | ≡ 1 lb⋅ft2/s2 | = Template:Val |
pound force-inch | lbf⋅in | ≡ g0 × 1 lb × 1 in | = Template:Val |
kilogram force-meter | kgf⋅m | ≡ g0 × N × m | = Template:Val |
Newton metre (SI unit) | N⋅m | ≡ N × m = kg⋅m2/s2 | = Template:Val |
Energy
Name of unit | Symbol | Definition | Relation to SI units |
---|---|---|---|
barrel of oil equivalent | boe | ≈ Template:Val | ≈ Template:Val |
British thermal unit (ISO) | BTUISO | ≡ Template:Val | = Template:Val |
British thermal unit (International Table) | BTUIT | = Template:Val | |
British thermal unit (mean) | BTUmean | ≈ Template:Val | |
British thermal unit (thermochemical) | BTUth | ≈ Template:Val | |
British thermal unit (39 °F) | BTU39 °F | ≈ Template:Val | |
British thermal unit (59 °F) | BTU59 °F | ≡ Template:Val | = Template:Val |
British thermal unit (60 °F) | BTU60 °F | ≈ Template:Val | |
British thermal unit (63 °F) | BTU63 °F | ≈ Template:Val | |
calorie (International Table) | calIT | ≡ Template:Val | = Template:Val |
calorie (mean) | calmean | Template:Frac of the energy required to warm one gram of air-free water from 0 °C to 100 °C at a pressure of 1 atm | ≈ Template:Val |
calorie (thermochemical) | calth | ≡ 4.184 J | = Template:Val |
Calorie (US; FDA) | Cal | ≡ 1 kcal = Template:Val | = Template:Val |
calorie (3.98 °C) | cal3.98 °C | ≈ Template:Val | |
calorie (15 °C) | cal15 °C | ≡ 4.1855 J | = Template:Val |
calorie (20 °C) | cal20 °C | ≈ Template:Val | |
Celsius heat unit (International Table) | CHUIT | ≡ 1 BTUIT × 1 K/°R | = Template:Val |
cubic centimetre of atmosphere; standard cubic centimetre | cc atm; scc | ≡ 1 atm × 1 cm3 | = Template:Val |
cubic foot of atmosphere; standard cubic foot | cu ft atm; scf | ≡ 1 atm × 1 ft3 | = Template:Val |
cubic foot of natural gas | ≡ Template:Val | = Template:Val | |
cubic yard of atmosphere; standard cubic yard | cu yd atm; scy | ≡ 1 atm × 1 yd3 | = Template:Val |
electronvolt | eV | ≡ e × 1 V | ≡ Template:Val |
erg (CGS unit) | erg | ≡ 1 g⋅cm2/s2 | = 10−7 J |
foot-pound force | ft lbf | ≡ g0 × 1 lb × 1 ft | = Template:Val |
foot-poundal | ft pdl | ≡ 1 lb⋅ft2/s2 | = Template:Val |
gallon-atmosphere (imperial) | imp gal atm | ≡ 1 atm × 1 gal (imp) | = Template:Val |
gallon-atmosphere (US) | US gal atm | ≡ 1 atm × 1 gal (US) | = Template:Val |
hartree, atomic unit of energy | Eh | ≡ me⋅α2⋅c2 (= 2 Ry) | ≈ Template:Val |
horsepower-hour | hp⋅h | ≡ 1 hp × 1 h | = Template:Val |
inch-pound force | in lbf | ≡ g0 × 1 lb × 1 in | = Template:Val |
joule (SI unit) | J | The work done when a force of one newton moves the point of its application a distance of one metre in the direction of the force.[19] | = 1 J = 1 m⋅N = 1 kg⋅m2/s2 = 1 C⋅V = 1 W⋅s |
kilocalorie; large calorie | kcal; Cal | ≡ Template:Val | = Template:Val |
kilowatt-hour; Board of Trade Unit | kW⋅h; B.O.T.U. | ≡ 1 kW × 1 h | = Template:Val |
litre-atmosphere | l atm; sl | ≡ 1 atm × 1 L | = Template:Val |
quad | ≡ 1015 BTUIT | = Template:Val | |
rydberg | Ry | ≡ R∞⋅ℎ⋅c | ≈ Template:Val |
therm (E.C.) | ≡ Template:Val | = Template:Val | |
therm (US) | ≡ Template:Val | = Template:Val | |
thermie | th | ≡ 1 McalIT | = Template:Val |
tonne of coal equivalent | TCE | ≡ 7 Gcalth | = Template:Val |
tonne of oil equivalent | toe | ≡ 10 GcalIT | = Template:Val |
ton of TNT | tTNT | ≡ 1 Gcalth | = Template:Val |
watt hour | W⋅h | ≡ 1 W × 1 h | = Template:Val |
watt second | W⋅s | ≡ 1 J | = Template:Val |
Power or heat flow rate
Name of unit | Symbol | Definition | Relation to SI units |
---|---|---|---|
atmosphere-cubic centimetre per minute | atm ccmTemplate:Citation needed | ≡ 1 atm × 1 cm3/min | = Template:Val |
atmosphere-cubic centimetre per second | atm ccsTemplate:Citation needed | ≡ 1 atm × 1 cm3/s | = Template:Val |
atmosphere-cubic foot per hour | atm cfhTemplate:Citation needed | ≡ 1 atm × 1 cu ft/h | = Template:Val |
atmosphere-cubic foot per minute | atm cfmTemplate:Citation needed | ≡ 1 atm × 1 cu ft/min | = Template:Val |
atmosphere-cubic foot per second | atm cfsTemplate:Citation needed | ≡ 1 atm × 1 cu ft/s | = Template:Val |
BTU (International Table) per hour | BTUIT/h | ≡ 1 BTUIT/h | ≈ Template:Val |
BTU (International Table) per minute | BTUIT/min | ≡ 1 BTUIT/min | ≈ Template:Val |
BTU (International Table) per second | BTUIT/s | ≡ 1 BTUIT/s | = Template:Val |
calorie (International Table) per second | calIT/s | ≡ 1 calIT/s | = Template:Val |
erg per second | erg/s | ≡ 1 erg/s | = Template:Val |
foot-pound-force per hour | ft⋅lbf/h | ≡ 1 ft lbf/h | ≈ Template:Val |
foot-pound-force per minute | ft⋅lbf/min | ≡ 1 ft lbf/min | = Template:Val |
foot-pound-force per second | ft⋅lbf/s | ≡ 1 ft lbf/s | = Template:Val |
horsepower (boiler) | hp | ≈ 34.5 lb/h × 970.3 BTUIT/lb | ≈ Template:Val[22] |
horsepower (European electrical) | hp | ≡ 75 kp⋅m/s | = Template:ValTemplate:Citation needed |
horsepower (electrical) | hp | ≡ 746 W | = Template:Val[22] |
horsepower (mechanical) | hp | ≡ 550 ft⋅lbf/s[22] | = Template:Val |
horsepower (metric) | hp or PS | ≡ 75 m⋅kgf/s | = Template:Val[22] |
litre-atmosphere per minute | L·atm/min | ≡ 1 atm × 1 L/min | = Template:Val |
litre-atmosphere per second | L·atm/s | ≡ 1 atm × 1 L/s | = Template:Val |
lusec | lusec | ≡ 1 L·µmHg/s [5] | ≈ Template:Val |
poncelet | p | ≡ 100 m⋅kgf/s | = Template:Val |
square foot equivalent direct radiation | sq ft EDR | ≡ 240 BTUIT/h | ≈ Template:Val |
ton of air conditioning | ≡ Template:Val of ice melted / 24 h | ≈ Template:Val | |
ton of refrigeration (imperial) | ≡ Template:Val × iceIT / 24 h: iceIT = 144 °F × 2326 J/kg⋅°F | ≈ Template:Val | |
ton of refrigeration (IT) | ≡ Template:Val × iceIT / 24 h: iceIT = 144 °F × 2326 J/kg⋅°F | ≈ Template:Val | |
watt (SI unit) | W | The power which in one second of time gives rise to one joule of energy.[19] | = Template:Val = 1 J/s = 1 N⋅m/s = 1 kg⋅m2/s3 |
Action
Name of unit | Symbol | Definition | Relation to SI units |
---|---|---|---|
atomic unit of action | au | ≡ ℏ ≡ Template:Frac | ≈ Template:Val[23] |
Dynamic viscosity
Name of unit | Symbol | Definition | Relation to SI units |
---|---|---|---|
pascal second (SI unit) | Pa⋅s | ≡ N⋅s/m2, kg/(m⋅s) | = 1 Pa⋅s |
poise (CGS unit) | P | ≡ 1 barye⋅s | = 0.1 Pa⋅s |
pound per foot hour | lb/(ft⋅h) | ≡ 1 lb/(ft⋅h) | ≈ Template:Val |
pound per foot second | lb/(ft⋅s) | ≡ 1 lb/(ft⋅s) | ≈ Template:Val |
pound-force second per square foot | lbf⋅s/ft2 | ≡ 1 lbf⋅s/ft2 | ≈ Template:Val |
pound-force second per square inch | lbf⋅s/in2 | ≡ 1 lbf⋅s/in2 | ≈ Template:Val |
Kinematic viscosity
Name of unit | Symbol | Definition | Relation to SI units |
---|---|---|---|
square foot per second | ft2/s | ≡ 1 ft2/s | = Template:Val |
square metre per second (SI unit) | m2/s | ≡ 1 m2/s | = 1 m2/s |
stokes (CGS unit) | St | ≡ 1 cm2/s | = 10−4 m2/s |
Electric current
Name of unit | Symbol | Definition | Relation to SI units |
---|---|---|---|
ampere (SI base unit) | A | ≡ one coulomb of charge going past a given point per second.[24] | (SI base unit) |
electromagnetic unit; abampere (CGS unit) | abamp | ≘ 10 A | = 10 A |
esu per second; statampere (CGS unit) | esu/s | ≘ (10 A⋅cm/s) / c | ≈ Template:Val |
Electric charge
Name of unit | Symbol | Definition | Relation to SI units |
---|---|---|---|
abcoulomb; electromagnetic unit (CGS unit) | abC; emu | ≘ 10 C | = 10 C |
atomic unit of charge | au | ≡ e | = Template:Val |
coulomb | C | ≡ charge of exactly 1/(Template:Val) elementary charges[24] | = 1 C = 1 A⋅s |
faraday | F | ≡ 1 mol × NA⋅e | ≈ Template:Val |
milliampere hour | mA⋅h | ≡ 0.001 A × 1 h | = 3.6 C |
statcoulomb; franklin; electrostatic unit (CGS unit) | statC; Fr; esu | ≘ (10 A⋅cm) / c | ≈ Template:Val |
Electric dipole
Name of unit | Symbol | Definition | Relation to SI units |
---|---|---|---|
atomic unit of electric dipole moment | ea0 | ≈ Template:Val[25] | |
coulomb-meter | C⋅m | = 1 C⋅m | |
debye | D | ≡ 10−10 esu⋅Å | ≘ Template:Val[26] |
Electromotive force, electric potential difference
Name of unit | Symbol | Definition | Relation to SI units |
---|---|---|---|
abvolt (CGS unit) | abV | ≘ 10−8 V | = 10−8 V |
statvolt (CGS unit) | statV | ≘ c⋅(1 μJ/A⋅m) | = Template:Val |
volt (SI unit) | V | The difference in electric potential across two points along a conducting wire carrying one ampere of constant current when the power dissipated between the points equals one watt.[19] | = 1 V = 1 W/A Template:Nowrap = 1 J/C |
Electrical resistance
Name of unit | Symbol | Definition | Relation to SI units |
---|---|---|---|
ohm (SI unit) | Ω | The resistance between two points in a conductor when one volt of electric potential difference, applied to these points, produces one ampere of current in the conductor.[19] | = 1 Ω = 1 V/A Template:Nowrap |
Capacitance
Name of unit | Symbol | Definition | Relation to SI units |
---|---|---|---|
farad (SI unit) | F | The capacitance between two parallel plates that results in one volt of potential difference when charged by one coulomb of electricity.[19] | = 1 F = 1 C/V Template:Nowrap |
Magnetic flux
Name of unit | Symbol | Definition | Relation to SI units |
---|---|---|---|
maxwell (CGS unit) | Mx | ≘ 10−8 Wb[22] | = 10−8 Wb |
weber (SI unit) | Wb | Magnetic flux which, linking a circuit of one turn, would produce in it an electromotive force of 1 volt if it were reduced to zero at a uniform rate in 1 second.[19] | = 1 Wb = 1 V⋅s Template:Nowrap |
Magnetic flux density
Name of unit | Symbol | Definition | Relation to SI units |
---|---|---|---|
gauss (CGS unit) | G | ≡ Mx/cm2 ≘ 10−4 T | = 10−4 T [27] |
tesla (SI unit) | T | ≡ Wb/m2 | = 1 T = 1 Wb/m2 Template:Nowrap |
Inductance
Name of unit | Symbol | Definition | Relation to SI units |
---|---|---|---|
henry (SI unit) | H | The inductance of a closed circuit that produces one volt of electromotive force when the current in the circuit varies at a uniform rate of one ampere per second.[19] | = 1 H = 1 Wb/A Template:Nowrap |
Temperature
Name of unit | Symbol | Definition | Relation to SI units |
---|---|---|---|
degree Celsius | °C | [°C] ≡ [K] − 273.15 | [K] ≡ [°C] + 273.15 |
degree Delisle | °De | [K] = 373.15 − [°De] × Template:Frac | |
degree Fahrenheit | °F | [°F] ≡ [°C] × Template:Frac + 32 | [K] ≡ ([°F] + 459.67) × Template:Frac |
degree Newton | °N | [K] = [°N] × Template:Frac + 273.15 | |
degree Rankine | °R; | [°R] ≡ [K] × Template:Frac | [K] ≡ [°R] × 5/9 |
degree Réaumur | °Ré | [K] = [°Ré] × Template:Frac + 273.15 | |
degree Rømer | °Rø | [K] = ([°Rø] − 7.5) × Template:Frac + 273.15 | |
Regulo Gas Mark | GM | [°F] ≡ [GM] × 25 + 300 | [K] ≡ [GM] × Template:Frac + 422.038 |
kelvin (SI base unit) | K | ≡ change in the thermodynamic temperature T that results in a change of thermal energy kT by 1.380 649 × 10−23 J.[28] | (SI base unit) |
Information entropy
Name of unit | Symbol | Definition | Relation to SI units | Relation to bits |
---|---|---|---|---|
natural unit of information; nit; nepit | nat | |||
shannon | Sh | ≡ ln(2) × nat | ≈ Template:Val | = 1 bit |
hartley; ban | Hart; ban | ≡ ln(10) × nat | ≈ Template:Val | |
bit | bit; b | = 1 bit | ||
nibble | ≡ 4 bits | = 22 bit | ||
byte | B | ≡ 8 bits | = 23 bit | |
kilobyte (decimal) | kB | ≡ Template:Val | = Template:Val bit | |
kibibyte (kilobyte) | KiB; KB | ≡ Template:Val | = 213 bit = Template:Val bit |
Modern standards (such as ISO 80000) prefer the shannon to the bit as a unit for a quantity of information entropy, whereas the (discrete) storage space of digital devices is measured in bits. Thus, uncompressed redundant data occupy more than one bit of storage per shannon of information entropy. The multiples of a bit listed above are usually used with this meaning.
Luminous intensity
The candela is the preferred nomenclature for the SI unit.
Name of unit | Symbol | Definition | Relation to SI units |
---|---|---|---|
candela (SI base unit) | cd | The luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540Template:E hertz and that has a radiant intensity in that direction of 1/683 watt per steradian.[24] | (SI base unit) |
candlepower (new) | cp | ≡ cd The use of candlepower as a unit is discouraged due to its ambiguity. | = 1 cd |
candlepower (old, pre-1948) | cp | Varies and is poorly reproducible.[29] Approximately 0.981 cd.[5] | ≈ 0.981 cd |
Luminance
Name of unit | Symbol | Definition | Relation to SI units |
---|---|---|---|
candela per square foot | cd/ft2 | ≡ cd/ft2 | ≈ Template:Val |
candela per square inch | cd/in2 | ≡ cd/in2 | ≈ Template:Val |
candela per square metre (SI unit); nit (deprecated[5]) | cd/m2 | ≡ cd/m2 | = 1 cd/m2 |
footlambert | fL | ≡ (1/π) cd/ft2 | ≈ Template:Val |
lambert | L | ≡ (104/π) cd/m2 | ≈ Template:Val |
stilb (CGS unit) | sb | ≡ 104 cd/m2 | = 104 cd/m2 |
Luminous flux
Name of unit | Symbol | Definition | Relation to SI units |
---|---|---|---|
lumen (SI unit) | lm | The luminous flux of a source that emits monochromatic radiation of frequency 540Template:E hertz and that has a radiant flux of 1/683 watt.[24] | = 1 lm = 1 cd⋅sr |
Illuminance
Name of unit | Symbol | Definition | Relation to SI units |
---|---|---|---|
footcandle; lumen per square foot | fc | ≡ lm/ft2 | = Template:Val |
lumen per square inch | lm/in2 | ≡ lm/in2 | ≈ Template:Val |
lux (SI unit) | lx | ≡ lm/m2 | = 1 lx = 1 lm/m2 |
phot (CGS unit) | ph | ≡ lm/cm2 | = 104 lx |
Radiation – source activity
Name of unit | Symbol | Definition | Relation to SI units |
---|---|---|---|
becquerel (SI unit) | Bq | ≡ Number of disintegrations per second | = 1 Bq = 1/s |
curie | Ci | ≡ Template:Val[30] | = Template:Val |
rutherford (H) | Rd | ≡ 1 MBq | = 106 Bq |
Although becquerel (Bq) and hertz (Hz) both ultimately refer to the same SI base unit (s−1), Hz is used only for periodic phenomena (i.e. repetitions at regular intervals), and Bq is only used for stochastic processes (i.e. at random intervals) associated with radioactivity.[31]
Radiation – exposure
Name of unit | Symbol | Definition | Relation to SI units |
---|---|---|---|
roentgen | R | 1 R ≡ Template:Val[22] | = Template:Val |
The roentgen is not an SI unit and the NIST strongly discourages its continued use.[32]
Radiation – absorbed dose
Name of unit | Symbol | Definition | Relation to SI units |
---|---|---|---|
gray (SI unit) | Gy | ≡ 1 J/kg[33] | = 1 Gy = 1 J/kg = 1 m2⋅s2 |
rad | rad | ≡ 0.01 Gy[22] | = 0.01 Gy |
Radiation – equivalent dose
Name of unit | Symbol | Definition | Relation to SI units |
---|---|---|---|
Röntgen equivalent man | rem | ≡ 0.01 Sv | = 0.01 Sv |
sievert (SI unit) | Sv | ≡ 1 J/kg[31] | = 1 Sv = 1 J/kg = 1 m2⋅s2 |
Although the definitions for sievert (Sv) and gray (Gy) would seem to indicate that they measure the same quantities, this is not the case. The effect of receiving a certain dose of radiation (given as Gy) is variable and depends on many factors, thus a new unit was needed to denote the biological effectiveness of that dose on the body; this is known as the equivalent dose and is shown in Sv. The general relationship between absorbed dose and equivalent dose can be represented as
- H = Q ⋅ D
where H is the equivalent dose, D is the absorbed dose, and Q is a dimensionless quality factor. Thus, for any quantity of D measured in Gy, the numerical value for H measured in Sv may be different.
Licensing
Content obtained and/or adapted from:
- Conversion of units, Wikipedia under a CC BY-SA license
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