metre.info - Tables of all metric measures and prefixes

Tables of Units and Prefixes

Overview of all modern weights and measures

Please click on the unit names to go to the encyclopaedia entries for more information.

Go to: Base units, derived units, prefixes, additional units.

Download these tables as Microsoft Word Document.

(A quick and handy reference sheet of all modern measurement units and prefixes. Prints out on two A4 sheets. 91 kibibytes.)

SI Base Units

Name	Symbol	Unit of
meter	m	length
kilogram	kg	mass
second	s	time
ampere	A	electric current
kelvin	K	thermodynamic temperature
mole	mol	amount of substance
candela	cd	luminous intensity

SI Derived Units

Name	Symbol	Unit of	Equivalent in Base Units	Other Equivalents
becquerel	Bq	activity (of a radionuclide)	1/s	—
coulomb	C	quantity of electricity, electric charge	A∙s	F∙V = J/V
degree Celsius	°C	Celsius temperature	K	K – 273.15
farad	F	capacitance	A²∙s⁴/kg∙m²	C/V=A∙s/V
gray	Gy	absorbed dose, specific energy imparted, kerma	m²/s²	J/kg
henry	H	inductance	kg∙m²/A²∙s²	Wb/A = V∙s/A
hertz	Hz	frequency	1/s	—
joule	J	energy, work, quantity of heat	kg∙m²/s²	N∙m = W∙s = Pa∙m³
katal	kat	catalytic activity	mol/s	—
lumen	lm	luminous flux	cd	cd∙(4∙π sr) = lx∙m²
lux	lx	illuminance	cd/m²	cd∙(4∙π sr)/m² = lm/m²
newton	N	force	kg∙m/s²	J/m = W∙s/m = Pa∙m²
ohm	W	electric resistance	kg∙m²/A²∙s³	V/A = 1/S
pascal	Pa	pressure, stress	kg/m·s²	N/m² = J/m³
radian	rad	plane angle	1	1/(2∙p) of a circle
siemens	S	electric conductance	A²∙s³/kg∙m²	A/V = 1/W
sievert	Sv	dose equivalent	m²/s²	J/kg
steradian	sr	solid angle	1	1/(4∙p) of a sphere
tesla	T	magnetic flux density	kg/A∙s²	Wb/m² = N/A∙m
volt	V	electric potential difference, electromotive force	kg∙m²/A∙s³	W/A = J/C = Wb/s
watt	W	power, radiant flux	kg∙m²/s³	J/s = V∙A = N∙m/s
weber	Wb	magnetic flux	kg∙m²/A∙s²	V∙s = H∙A = T∙m² = J/A

The Prefixes of the SI

yotta	[Y]	1 000 000 000 000 000 000 000 000	= 10²⁴	(one septillion)
zetta	[Z]	1 000 000 000 000 000 000 000	= 10²¹	(one sextillion)
exa	[E]	1 000 000 000 000 000 000	= 10¹⁸	(one quintillion)
peta	[P]	1 000 000 000 000 000	= 10¹⁵	(one quadrillion)
tera	[T]	1 000 000 000 000	= 10¹²	(one trillion)
giga	[G]	1 000 000 000	= 10⁹	(one billion)
mega	[M]	1 000 000	= 10⁶	(one million)
kilo	[k]	1 000	= 10³	(one thousand)
		1	= 10⁰	(one)
milli	[m]	0.001	= 10⁻³	(one thousandth)
micro	[m]	0.000 001	= 10⁻⁶	(one millionth)
nano	[n]	0.000 000 001	= 10⁻⁹	(one billionth)
pico	[p]	0.000 000 000 001	= 10⁻¹²	(one trillionth)
femto	[f]	0.000 000 000 000 001	= 10⁻¹⁵	(one quadrillionth)
atto	[a]	0.000 000 000 000 000 001	= 10⁻¹⁸	(one quintillionth)
zepto	[z]	0.000 000 000 000 000 000 001	= 10⁻²¹	(one sextillionth)
yocto	[y]	0.000 000 000 000 000 000 000 001	= 10⁻²⁴	(one septillionth)

All SI prefixes above are multiples or sub-multiples of 1 000. The usage of the four SI prefixes below is by custom limited to non-technical measurements of length, area and volume.

hecto	[h]	100	= 10²	(one hundred)
deca	[da]	10	= 10¹	(ten)
		1	= 10⁰	(one)
deci	[d]	0.1	= 10⁻¹	(one tenth)
centi	[c]	0.01	= 10⁻²	(one hundredth)

Units used with the SI

Name	Symbol	Unit of	Equivalents in Base Units	Other Equivalents
minute	min	time	60 s	—
hour	h	time	3 600 s	60 min
day	d	time	86 400 s	24 h = 1 440 min
degree of arc	°	plane angle	(2∙p/360) rad	60′ » 0.017 453 rad
minute of arc	′	plane angle	(2∙p/21 600) rad	60″ » 0.290 888∙10⁻³ rad
second of arc	″	plane angle	(2∙p/1 296 000) rad	» 4.848 137∙10⁻⁶ rad
liter	l or L	volume	0.001 m³	1 000 cm³ = 1 000 000 mm³
tonne	t	mass	1 000 kg	1 000 000 g = 1 Mg
bel	B	logarithmic quantities such as field level, power level, sound pressure level, attenuation	1	0.5∙(ln 10) Np » 1.151 292 Np
neper	Np	logarithmic quantities such as field level, power level, sound pressure level, logarithmic decrement	1	2/(ln 10) B » 0.868 588 B

Three other units whose values are obtained experimentally, are accepted for use with the SI:

§ electronvolt [eV] 1 eV = 1.602 177 33∙10^-19 J

§ unified atomic mass unit [u] 1 u = 1.660 540 2∙10^-27 kg

§ astronomical unit [ua] 1 ua = 1.495 978 706 91∙10¹¹ m