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The following units are not SI units but are "accepted for use with the International System."

Non-SI units accepted for use with SI

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Name	Symbol	Quantity	Equivalent SI unit
minute	min	time	1 min = 60 s
hour	h	time	1 h = 60 min = 3600 s
day	d	time	1 d = 24 h = 1440 min = 86400 s
degree of arc	°	angle	1° = (π/180) rad
minute of arc	′	angle	1′ = (1/60)° = (π/10800) rad
second of arc	″	angle	″ = (1/60)′ = (1/3600)° = (π/648000) rad
litre	l or L	volume	1dm3 = 0.001 m3
tonne	t	mass	1 t = 103 kg

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
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
hectare	ha	area	1 ha = 100 a = 10000 m2
bar	bar	pressure	1 bar = 105 Pa
Ångström, angstrom	Å	length	1 Å = 0.1 nm = 10−10 m
barn	b	area	1 b = 10−28 m2

[edit] References

Taylor, Barry N. (ed.) (2001). The International System of Units (SI) (2001 ed., Special Publication 330). Gaithersburg, Maryland: National Institute of Standards and Technology. pp. 15–19. Viewed at http://physics.nist.gov/Pubs/SP330/sp330.pdf