Wiktionary Appendix:SI units

Table of contents

1 SI units 1.1 Base units (with symbols in parentheses) 1.2 Derived units (with symbols in parentheses) 1.3 Alternative names for SI units and their multiples and submultiples 1.4 Former names for SI units 2 SI prefixes (with symbols in parentheses) 2.1 Former prefixes 3 Commonly used multiples of units

SI units

SI is an abbreviation of Système International (d'Unités) [International System (of Units)] and is a standard metric system of units adopted for official scientific use. For more information, see Wikipedia's article on SI .

Note: this page is simply a collection of links to the names of SI units and their prefixes and multiples. For further information, see the Wikipiedia articles SI base units and SI derived units .

Base units (with symbols in parentheses)

• ampere (A)
• candela (cd)
• kelvin (K)
• kilogram, kilogramme (kg)
• metre (Commonwealth English), meter (US English) (m)
• mole (mol)
• second (s)

Derived units (with symbols in parentheses)

• becquerel (Bq)
• coulomb (C)
• degree Celsius (°C)
• farad (F)
• gray (Gy)
• henry (H)
• hertz (Hz)
• joule (J)
• katal (kat)
• lumen (lm)
• lux (lx)
• newton (N)
• ohm (Ω)
• pascal (Pa)
• radian (rad) (classified as a supplementary unit until 1995)
• siemens (S)
• sievert (Sv)
• steradian (sr) (classified as a supplementary unit until 1995)
• tesla (T)
• volt (V)
• watt (W)
• weber (Wb)

Alternative names for SI units and their multiples and submultiples

• cycle (alternative of hertz)
• Multiples:
  • kilocycle
  • megacycle
• cycle per second (alternative name for hertz)
  • kilocycle per second
  • megacycle per second
• micron (alternative name for micrometre/micrometer )

Former names for SI units

• degree kelvin
• new candle

SI prefixes (with symbols in parentheses)

• atto- (a)
• centi- (c)
• deca- (also deka-) (da)
• deci- (d)
• deka- (also deca-) (da)
• exa- (E)
• exbi- (Ei)
• femto- (f)
• gibi- (Gi)
• giga- (G) (or gig- before a vowel, as in gigohm )
• hecto- (h)
• kibi- (Ki)
• kilo- (k)
• mebi- (Mi)
• mega- (M) (or meg- before a vowel, as in megohm)
• micro- (μ, u)
• milli- (m)
• myria- (my)
• nano- (n)
• pebi- (Pi)
• peta- (P)
• pico- (p)
• tebi- (Ti)
• tera- (T)
• yocto- (y)
• yotta- (Y)
• zepto- (z)
• zetta- (Z)

The prefixes kibi-, mebi-, gibi-, tebi-, pebi-, and exbi- were adopted by the IEC and NIST to express binary multiples.

Former prefixes

• millimilli-
• millimicro-
• micromicro-

Commonly used multiples of units

The table below shows which prefixes are most commonly used with each unit. In theory, any combination of a prefix and a unit is possible. In practice, only those multiples that are of practical use are used. Multiples towards the left and right of the table tend to gain currency as advances in technology and miniaturisation make them meaningful.

Links are to combinations that are in relatively common scientific use. Blank entries indicate combinations that are rare or not used.

Notes:

1. Units are ordered alphabetically by their symbol. Prefixes are ordered from largest to smallest.
2. It is the gram (g) that takes prefixes, not the kilogram.
3. Some combinations have special names; for example, 10⁶ grams is called a tonne, not a "megagram".
4. The multiples in the grey columns are not in official scientific usage.
5. The table lists multiples of SI units only. Other units that use the SI prefixes, such as kilobyte and millibar, are not given here.
6. The table is currently incomplete. More links will be added later.

(Sources: Wikipedia ; Oxford English Dictionary, 2nd ed.)

Commonly used multiples of SI units

Y	Z	E	P	T	G	M	k	h	da	Unit	d	c	m	μ	n	p	f	a	z	y
						MA	kA			A			mA	μA	nA
										Bq
										C
										°C
										cd
										F			mF	μF	nF	pF
						t	kg	hg	dag	g	dg	cg	mg	μg
										Gy
										H			mH	μH	nH
			PHz	THz	GHz	MHz	kHz			Hz
							kJ			J
										K
										kat
										lm
										lx
							km	hm	dam	m	dm	cm	mm	μm	pm	fm
										mol			mmol	μmol
										N
					GΩ	MΩ	kΩ			Ω			mΩ
							kPa	hPa		Pa
										rad
										S
										s			ms	μs	ns	ps	fs	as
										sr
										Sv			mSv	μSv
										T			mT	μT
						MV	kV			V			mV	μV
					GW	MW	kW			W			mW	μW
							kWb			Wb			mWb	μWb