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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, 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.

Units officially accepted for use with the SI

Name	Symbol	Quantity	Equivalent SI unit
Widely used units expected to be used indefinitely
minute	min	time (SI unit multiple)	1 min = 60 s
hour	h	time (SI unit multiple)	1 h = 60 min = 3600 s
day	d	time (SI unit multiple)	1 d = 24 h = 1440 min = 86400 s
degree	°	plane angle (dimensionless unit)	1° = (π / 180) rad
minute	′	plane angle (dimensionless unit)	1′ = (1 / 60)° = (π / 10800) rad
second	″	plane angle (dimensionless unit)	1″ = (1 / 60)′ = (1 / 3600)° = (π / 648000) rad
hectare	ha	area (decimal unit multiple)	1 ha = 100 a = 10000 m2 = 1 hm2
litre	l or L	volume (decimal unit multiple)	1 L = 1 dm3 = 0.001 m3 = 1000 cc = 1000 cm3
tonne	t	mass (decimal unit multiple)	1 t = 103 kg = 1 Mg
Logarithmic units
neper	Np	level of a field quantity	LF = ln(F / F0) Np
		level of a power quantity	LP = 1⁄2 ln(P / P0) Np
bel, decibel	B, dB	level of a field quantity	LF = 2 log10(F / F0) B
		level of a power quantity	LP = log10(P / P0) B
Units with experimentally determined values
electronvolt	eV	energy	1 eV = 6981160217652999999♠1.60217653(14)×10−19 J
unified atomic mass unit dalton	u Da	mass	1 u = 1 Da = 6973166053886000000♠1.66053886(28)×10−27 kg
astronomical unit	ua	length	1 ua = 7011149597870691000♠1.49597870691(6)×1011 米
Natural units (n.u.)
n.u. of speed (speed of light in vacuum)	c0	speed	7008299792458000000♠299792458 m/s (exact)
n.u. of action (reduced Planck constant)	ħ	action	6966105457168000000♠1.05457168(18)×10−34 J·s
n.u. of mass (electron mass)	me	mass	6969910938260000000♠9.1093826(16)×10−31 kg
n.u. of time	ħ / mec02	time	6979128808866770000♠1.2880886677(86)×10−21 s
Atomic units (a.u.)
a.u. of charge (elementary charge)	e	electric charge	6981160217652999999♠1.60217653(14)×10−19 C
a.u. of mass (electron mass)	me	mass	6969910938260000000♠9.1093826(16)×10−31 kg
a.u. of action (reduced Planck constant)	ħ	action	6966105457168000000♠1.05457168(18)×10−34 J·s
a.u. of length, bohr (Bohr radius)	a0	length	6989529177210800000♠0.5291772108(18)×10−10 米
a.u. of energy, hartree (Hartree energy)	Eh	energy	6982435974417000000♠4.35974417(75)×10−18 J
a.u. of time	ħ / Eh	time	6983241888432650500♠2.418884326505(16)×10−17 s

Common units not officially sanctioned

Name	Symbol	Quantity	Equivalent SI unit
ångström, angstrom	Å	length	1 Å = 0.1 nm = 10−10 m
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
atmosphere	atm	pressure	1 atm = 1013.25 mbar = 1013.25 hPa = 7005101325000000000♠101325 Pa exactly (commonly used in atmospheric meteorology, in oceanography and for pressures within liquids, or in the industry for pressures within containers of liquefied gas)
dyne per square centimetre (barye)	Ba	pressure	1 Ba = 0.1 Pa = 0.1 N/m2 = 100 g·cm−1·s−2
millimetre of mercury	mmHg	pressure	1 mmHg = 7002133322387415000♠133.322387415 Pa at 0 °C = 7002133322387415000♠133.322387415 N/m2 at 0 °C = 7002133322387415000♠133.322387415 kg·cm−1·s−2 at 0 °C
torr	Torr	pressure	1 Torr = 1/760 atm = 133.322368421... Pa = 133.322368421... N/m2 = 133.322368421... kg·cm−1·s−2

参见

• 伽
• 国际单位制（SI）
• 国际单位制基本单位
• 国际单位制导出单位
• 国际单位制词头