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, but are otherwise mentioned in the SI, because either the General Conference on Weights and Measures 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
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 8th SI brochure. The table below compares the status of each unit for which the status has changed between editions of the SI Brochure.| Name | Symbol | 8th SI Brochure | 9th SI Brochure |
| astronomical unit | au | accepted | accepted |
| unified atomic mass unit | u | accepted | footnote only |
| n.u. of speed | c0 | listed | not mentioned |
| n.u. of action | ħ | listed | not mentioned |
| n.u. of mass | me | listed | not mentioned |
| n.u. of time | ħ/ | listed | not mentioned |
| a.u. of charge | e | listed | not mentioned |
| a.u. of mass | me | listed | not mentioned |
| a.u. of action | ħ | listed | not mentioned |
| a.u. of length | a0 | listed | not mentioned |
| a.u. of energy | Eh | listed | not mentioned |
| a.u. of time | ħ/Eh | listed | not mentioned |
| bar | bar | listed | not mentioned |
| millimetre of mercury | mmHg | listed | not mentioned |
| ångström | Å | listed | not mentioned |
| nautical mile | M | listed | not mentioned |
| barn | b | listed | not mentioned |
| knot | kn | listed | not mentioned |
| erg | erg | listed | not mentioned |
| dyne | dyn | listed | not mentioned |
| poise | P | listed | not mentioned |
| stokes | st | listed | not mentioned |
| stilb | sb | listed | not mentioned |
| phot | ph | listed | not mentioned |
| gal | Gal | listed | footnote only |
| maxwell | Mx | listed | not mentioned |
| gauss | G | listed | not mentioned |
| œrsted | Oe | listed | not mentioned |
In this table, the status descriptions have the following meanings:
- "accepted": The unit is accepted for use with the SI.
- "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.
- "not mentioned": There is no mention of the unit in the brochure, excluding historical appendices.
Other units defined but not officially sanctioned
| Name | Symbol | Quantity | Equivalent SI unit |
| gal | Gal | acceleration | 1 Gal = 1 cm⋅s−2 = 0.01 m⋅s−2 |
| unified atomic mass unit | u | mass | 1 u = 1 Da = |
| volt-ampere reactive | var | reactive power | 1 var = 1 V⋅A |