User:Atavoidirc/SI
Unit accepted for use in the International System of Units
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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 Brochure[1] because 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 they are otherwise commonly encountered worldwide.
Units officially accepted for use with the SI
| Name | Symbol | Quantity | Value in SI units |
|---|---|---|---|
| minute | min | time | 1 min = 60 s |
| hour | h | time | 1 h = 60 min = 3 600 s |
| day | d | time | 1 d = 24 h = 1440 min = 86 400 s |
| astronomical unit | au | length | 1 au = 149 597 870 700 m |
| degree | ° | plane angle | 1° = (π/180) rad |
| minute | ′ | plane angle | 1′ = (1/60)° = (π/10 800) rad |
| second | ″ | plane angle | 1″ = (1/60)′ = (1/3 600)° = (π/648 000) rad |
| hectare | ha | area | 1 ha = 1 hm2 = 10 000 m2 |
| litre | l, L | volume | 1 l = 1 dm3 = 1 000 cm3 = 0.001 m3 |
| tonne | t | mass | 1 t = 1 Mg = 1 000 kg |
| dalton | Da | mass | 1 Da = 1.66053906892(52)×10−27 kg[2] = 1.660 539 066 60(50) yg[note 1] |
| electronvolt | eV | energy | 1 eV = 1.602176634×10−19 J = 160.217 663 4 zJ |
| neper | Np | logarithmic ratio quantity | — |
| bel, decibel | B, dB | logarithmic ratio quantity | — |
Changes to units mentioned in the SI
With the publication of the 9th SI brochure in 2019, the list of non-SI units listed in tables changed compared to the preceding SI brochures.[3] The table below compares the status of each unit for which the status has changed between editions of the SI Brochure.
| Name | Symbol | 1st-3rd SI Brochures | 4-6th SI Brochures | 7th SI Brochure | 8th SI Brochure | 9th SI Brochure |
|---|---|---|---|---|---|---|
| astronomical unit | au[note 2] | accepted | — | accepted | accepted | accepted |
| Parsec | pc | accepted | — | — | — | — |
| neper | Np | — | — | accepted | listed | accepted |
| bel | b | — | — | accepted | listed | accepted |
| decibel | db | — | — | — | listed | accepted |
| unified atomic mass unit | u | accepted | accepted | accepted | accepted | footnote only |
| dalton | Da | — | — | — | accepted | accepted |
| natural unit (n.u.) of speed | c0 | — | — | — | listed | — |
| n.u. of action | ħ | — | — | — | listed | — |
| n.u. of mass | me | — | — | — | listed | — |
| n.u. of time | ħ/(mec02) | — | — | — | listed | — |
| atomic unit (a.u.) of charge | e | — | — | — | listed | — |
| a.u. of mass | me | — | — | — | listed | — |
| a.u. of action | ħ | — | — | — | listed | — |
| a.u. of length | a0 | — | — | — | listed | — |
| a.u. of energy | Eh | — | — | — | listed | — |
| a.u. of time | ħ/Eh | — | — | — | listed | — |
| nautical mile | M | temporarily accepted | temporarily accepted | temporarily accepted | listed | — |
| knot | kn | temporarily accepted | temporarily accepted | temporarily accepted | listed | — |
| ångström | Å | temporarily accepted | temporarily accepted | temporarily accepted | listed | — |
| are | a | temporarily accepted | temporarily accepted | temporarily accepted | — | — |
| hectare | ha | temporarily accepted | temporarily accepted | temporarily accepted | accepted | accepted |
| barn | b | temporarily accepted | temporarily accepted | temporarily accepted | listed | — |
| bar | bar | temporarily accepted | temporarily accepted | temporarily accepted | listed | — |
| standard atmosphere | atm | temporarily accepted | listed | listed | — | — |
| gal | Gal | temporarily accepted | temporarily accepted | listed | listed | footnote only |
| curie | C | temporarily accepted | temporarily accepted | listed | — | — |
| roentgen | R | temporarily accepted | temporarily accepted | listed | — | — |
| rad | rad | temporarily accepted | temporarily accepted | listed | — | — |
| rem | rem | — | temporarily accepted | listed | — | — |
| erg | erg | listed | listed | listed | listed | — |
| dyne | dyn | listed | listed | listed | listed | — |
| poise | P | listed | listed | listed | listed | — |
| stokes | st | listed | listed | listed | listed | — |
| maxwell | Mx | listed | listed | listed | listed | — |
| gauss | G | listed | listed | listed | listed | — |
| ørsted | Oe | listed | listed | listed | listed | — |
| stilb | sb | listed | listed | listed | listed | — |
| phot | ph | listed | listed | listed | listed | — |
| fermi | listed | listed | listed | — | — | |
| carat | listed | listed | listed | — | — | |
| torr | listed | listed | listed | — | — | |
| kilogram-force | kgf | listed | listed | — | — | — |
| calorie | cal | listed | listed | listed | — | — |
| micron | μ | listed | listed | listed | — | — |
| x-unit | xu | listed | listed | — | — | — |
| stilb | sb | listed | listed | — | — | — |
| gamma (Mass) | γ | listed | listed | listed | — | — |
| γ (magnetic flux density) | γ | listed | listed | — | — | — |
| lambda | λ | listed | listed | — | — | — |
| jansky | Jy | — | — | listed | — | — |
| millimetre of mercury | mmHg | — | — | — | listed | — |
In this table, the status descriptions have the following meanings:
- "accepted": The unit is accepted for use with the SI.
- "temporarily accepted": The unit is accepted for use with the SI, but is planned to be phased out.
- "listed": The unit is defined in a table of units in the brochure but not accepted for use with the SI.
- "footnote only": The unit is defined in a footnote or side note, without any mention in the main text.
- "—": There is no mention of the unit in the brochure, excluding historical appendices.
Other units defined but not officially sanctioned
The following table lists units that are effectively defined in side- and footnotes in the 9th SI brochure. Units that are mentioned without a definition or that occur in historical material recorded in the appendices are not included.
| Name | Symbol | Quantity | Equivalent SI unit |
|---|---|---|---|
| gal[note 3] | Gal | acceleration | 1 Gal = 1 cm⋅s−2 = 0.01 m⋅s−2 |
| unified atomic mass unit[note 4] | u | mass | 1 u = 1 Da = 1.66053906892(52)×10−27 kg[2] |
| volt-ampere reactive | var | reactive power | 1 var = 1 V⋅A |