<P> 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, 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 . </P> <Table> <Tr> <Th> Name </Th> <Th> Symbol </Th> <Th> Quantity </Th> <Th> Equivalent SI unit </Th> </Tr> <Tr> <Td_colspan="4"> Widely used units expected to be used indefinitely </Td> </Tr> <Tr> <Td> minute </Td> <Td> min </Td> <Td> time (SI unit multiple) </Td> <Td> 1 min = 60 s </Td> </Tr> <Tr> <Td> hour </Td> <Td> h </Td> <Td> time (SI unit multiple) </Td> <Td> 1 h = 60 min = 3600 s </Td> </Tr> <Tr> <Td> day </Td> <Td> d </Td> <Td> time (SI unit multiple) </Td> <Td> 1 d = 24 h = 1440 min = 86400 s </Td> </Tr> <Tr> <Td> degree </Td> <Td> ° </Td> <Td> plane angle (dimensionless unit) </Td> <Td> 1 ° = (π / 180) rad </Td> </Tr> <Tr> <Td> minute </Td> <Td> ′ </Td> <Td> plane angle (dimensionless unit) </Td> <Td> 1 ′ = (1 / 60) ° = (π / 10800) rad </Td> </Tr> <Tr> <Td> second </Td> <Td>" </Td> <Td> plane angle (dimensionless unit) </Td> <Td> 1" = (1 / 60) ′ = (1 / 3600) ° = (π / 648000) rad </Td> </Tr> <Tr> <Td> hectare </Td> <Td> ha </Td> <Td> area (decimal unit multiple) </Td> <Td> 1 ha = 100 a = 10000 m = 1 hm </Td> </Tr> <Tr> <Td> litre </Td> <Td> l or L </Td> <Td> volume (decimal unit multiple) </Td> <Td> 1 L = 1 dm = 0.001 m = 1000 cm </Td> </Tr> <Tr> <Td> tonne </Td> <Td> </Td> <Td> mass (decimal unit multiple) </Td> <Td> 1 t = 10 kg = 1 Mg </Td> </Tr> <Tr> <Td> astronomical unit </Td> <Td> au or AU </Td> <Td> length </Td> <Td> 1 AU = 7011149597870700000 ♠ 1.495 978 707 × 10 m (exact) </Td> </Tr> <Tr> <Td_colspan="4"> Logarithmic units </Td> </Tr> <Tr> <Td> neper </Td> <Td> Np </Td> <Td> level of a field quantity </Td> <Td> 1 Np = 1 </Td> </Tr> <Tr> <Td> </Td> <Td> </Td> <Td> level of a power quantity </Td> <Td> 1 Np = 1 </Td> </Tr> <Tr> <Td> bel </Td> <Td> </Td> <Td> level of a field quantity </Td> <Td> 1 B = ln (10) / 2 Np = ln (10) / 2 </Td> </Tr> <Tr> <Td> </Td> <Td> </Td> <Td> level of a power quantity </Td> <Td> </Td> </Tr> <Tr> <Td> decibel </Td> <Td> dB </Td> <Td> level of a field quantity </Td> <Td> 1 dB = 0.1 B </Td> </Tr> <Tr> <Td> </Td> <Td> </Td> <Td> level of a power quantity </Td> <Td> </Td> </Tr> <Tr> <Td_colspan="4"> Units with experimentally determined values </Td> </Tr> <Tr> <Td> electronvolt </Td> <Td> eV </Td> <Td> energy </Td> <Td> 1 eV = 6981160217652999999 ♠ 1.602 176 53 (14) × 10 J </Td> </Tr> <Tr> <Td> unified atomic mass unit dalton </Td> <Td> u Da </Td> <Td> mass </Td> <Td> 1 u = 1 Da = 6973166053886000000 ♠ 1.660 538 86 (28) × 10 kg </Td> </Tr> <Tr> <Td_colspan="4"> Natural units (n.u.) </Td> </Tr> <Tr> <Td> n.u. of speed (speed of light in vacuum) </Td> <Td> </Td> <Td> speed </Td> <Td> 7008299792458000000 ♠ 299 792 458 m / s (exact) </Td> </Tr> <Tr> <Td> n.u. of action (reduced Planck constant) </Td> <Td> ħ </Td> <Td> action </Td> <Td> 6966105457168000000 ♠ 1.054 571 68 (18) × 10 J s </Td> </Tr> <Tr> <Td> n.u. of mass (electron mass) </Td> <Td> m </Td> <Td> mass </Td> <Td> 6969910938260000000 ♠ 9.109 3826 (16) × 10 kg </Td> </Tr> <Tr> <Td> n.u. of time </Td> <Td> ħ / m c </Td> <Td> time </Td> <Td> 6979128808866770000 ♠ 1.288 088 6677 (86) × 10 s </Td> </Tr> <Tr> <Td_colspan="4"> Atomic units (a.u.) </Td> </Tr> <Tr> <Td> a.u. of charge (elementary charge) </Td> <Td> </Td> <Td> electric charge </Td> <Td> 6981160217652999999 ♠ 1.602 176 53 (14) × 10 C </Td> </Tr> <Tr> <Td> a.u. of mass (electron mass) </Td> <Td> m </Td> <Td> mass </Td> <Td> 6969910938260000000 ♠ 9.109 3826 (16) × 10 kg </Td> </Tr> <Tr> <Td> a.u. of action (reduced Planck constant) </Td> <Td> ħ </Td> <Td> action </Td> <Td> 6966105457168000000 ♠ 1.054 571 68 (18) × 10 J s </Td> </Tr> <Tr> <Td> a.u. of length, bohr (Bohr radius) </Td> <Td> </Td> <Td> length </Td> <Td> 6989529177210800000 ♠ 0.529 177 2108 (18) × 10 m </Td> </Tr> <Tr> <Td> a.u. of energy, hartree (Hartree energy) </Td> <Td> </Td> <Td> energy </Td> <Td> 6982435974417000000 ♠ 4.359 744 17 (75) × 10 J </Td> </Tr> <Tr> <Td> a.u. of time </Td> <Td> ħ / E </Td> <Td> time </Td> <Td> 6983241888432650500 ♠ 2.418 884 326 505 (16) × 10 s </Td> </Tr> </Table>

Which is not a unit in the si system