Template:SI acceptable units

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Non-SI units accepted for use with SI
Name Symbol Quantity Equivalent SI unit
minute min time (multiple unit) 1 min = 60 s
hour h time (multiple unit) 1 h = 60 min = 3600 s
day d time (multiple unit) 1 d = 24 h = 1440 min = 86400 s
degree of arc ° angle (non unitary unit) 1° = (π/180) rad
minute of arc ′ angle (non unitary unit) 1′ = (1/60)° = (π/10800) rad
second of arc ″ angle (non unitary unit) 1″ = (1/60)′ = (1/3600)° = (π/648000) rad
square degree deg² or sq.deg. solid angle 1 deg² = (π/180) sr. This unit is mostly used in astronomy and optic (its usage is strongly discouraged in all other domains, including in cartography). The whole sphere covers a solid angle (seen from its centre) of (129600/π) deg² (approx. 41252.961 deg²) and is the solid angle covered by a conic section of a sphere, whose opening apex is exactly 360° (note that the measure of a solid angle in square degrees is not proportional (and does not vary polynomially with) the measure of the associated planar angle in degrees of opening of its associated cone. In cartography, you can't simply multiply a difference of longitudes and a difference of latitudes, both expressed in degrees to get an exact measure of a solid angle in square degrees (this will just be an approximation only if these differences are very small, below one minute of arc each, and the covered area is very near the equator, i.e. at very low latitudes where the small area will be nearly rectangular instead of being nearly trapezoidal in median latitudes, or nearly a disc sector near the poles).
hectare ha area (simple decimal multiple unit) 1 ha = 100 a = 10000 m²
litre l or L volume (simple decimal multiple unit) 1 dm3 = 0.001 m3
tonne t mass (simple decimal multiple unit) 1 t = 103 kg = 1 Mg
Non-SI units not formally adopted by the CGPM
Name Symbol Quantity Equivalent SI unit
neper, field quantity Np ratio (dimensionless) LF = ln(F/F0) Np
neper, power quantity Np ratio (dimensionless) LP = ½ ln(P/P0) Np
bel, field quantity B ratio (dimensionless) LF = 2 log10(F/F0) B
bel, power quantity B ratio (dimensionless) LP = log10(P/P0) B
Non-SI units with values obtained only by experiment
Name Symbol Quantity Equivalent SI unit
electronvolt eV energy 1 eV = 1.60217733 (49) × 10−19 J
atomic mass unit u mass 1 u = 1.6605402 (10) × 10−27 kg
astronomical unit AU length 1 AU = 1.49597870691 (30) × 1011 m
Non-SI units whose use is not encouraged
Name Symbol Quantity Equivalent SI unit
Ångström, angstrom Å length 1 Å = 0.1 nm = 10−10 m
nautical mile   length 1 nautical mile = 1852 m
knot   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 (was used in atmospheric meteorology, the preferred unit is now the hectopascal)
atmosphere atm pressure 1 atm = 1013.25 mbar = 1013.25 hPa] = 1.01325×105 Pa (commonly used in atmospheric meteorology, in oceanology and for pressures within liquids, or in the industry for pressures within containers of liquified gas)