66.8: SI Units

Table $\PageIndex{1}$: SI base units.

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

Table $\PageIndex{2}$: Derived SI units

Name	Symbol	Definition	Base Units	Quantity
radian	$\mathrm{rad}$	$\mathrm{m} / \mathrm{m}$	-	plane angle
steradian	$\mathrm{sr}$	$\mathrm{m}^2 / \mathrm{m}^2$	-	solid angle
newton	$\mathrm{N}$	$\mathrm{kg} \mathrm{m} \mathrm{s}^{-2}$	$\(\mathrm{~kg} \mathrm{~m} \mathrm{~s}^{-2}$	force
joule	$\mathrm{J}$	$\mathrm{N} \mathrm{m}$	$\mathrm{kg} \mathrm{m}^2 \mathrm{~s}^{-2}$	energy
watt	$\mathrm{W}$	$\mathrm{J} / \mathrm{s}$	$\mathrm{kg} \mathrm{m}^2 \mathrm{~s}^{-3}$	power
pascal	$\mathrm{Pa}$	$\mathrm{N} / \mathrm{m}^2$	$\mathrm{~kg} \mathrm{~m}^{-1} \mathrm{~s}^{-2}$	pressure
hertz	$\mathrm{Hz}$	$\mathrm{s}^{-1}$	$\mathrm{~s}^{-1}$	frequency
coulomb	$\mathrm{C}$	$\mathrm{A} \mathrm{s}$	$\mathrm{A} \mathrm{s}^2$	electric charge
volt	$\mathrm{V}$	$\mathrm{J} / \mathrm{C}$	$\mathrm{kg} \mathrm{m}^{-1} \mathrm{~A}^{-3}$	electric potential
ohm	$\Omega$	$\mathrm{V} / \mathrm{A}$	$\mathrm{kg} \mathrm{m}^2 \mathrm{~A}^{-2} \mathrm{~s}^{-3}$	electrical resistance
siemens	$\mathrm{S}$	$\mathrm{A} / \mathrm{V}$	$\mathrm{kg}^{-1} \mathrm{~m}^{-2} \mathrm{~A}^2 \mathrm{~s}^3$	electrical conductance
farad	$\mathrm{F}$	$\mathrm{C} / \mathrm{V}$	$\mathrm{kg}^{-1} \mathrm{~m}^{-2} \mathrm{~A}^2 \mathrm{~s}^4$	capacitance
weber	$\mathrm{Wb}$	$\mathrm{V} \mathrm{s}$	$\mathrm{kg} \mathrm{m}^2 \mathrm{~A}^{-1} \mathrm{~s}^{-2}$	magnetic flux
tesla	$\mathrm{T}$	$\mathrm{Wb} / \mathrm{m}^2$	$\mathrm{~kg} \mathrm{~A}^{-1} \mathrm{~s}^{-2}$	magnetic induction
henry	$\mathrm{H}$	$\mathrm{Wb} / \mathrm{A}$	$\mathrm{kg} \mathrm{m}^2 \mathrm{~A}^{-2} \mathrm{~s}^{-2}$	induction
lumen	$\mathrm{lm}$	$\mathrm{cd} \mathrm{sr}$	$\mathrm{cd} \mathrm{sr}^{-2}$	luminous flux
lux	$\mathrm{lx}$	$\mathrm{lm} / \mathrm{m}^2$	$\mathrm{~cd} \mathrm{sr} \mathrm{m}^{-2}$	illuminance
becquerel	$\mathrm{Bq}$	$\mathrm{s} \mathrm{s}^{-1}$	$\mathrm{~s}^{-1}$	radioactivity
gray	$\mathrm{Gy}$	$\mathrm{J} / \mathrm{kg}$	$\mathrm{m}^2 \mathrm{~s}^{-2}$	absorbed dose
sievert	$\mathrm{Sv}$	$\mathrm{J} / \mathrm{kg}$	$\mathrm{m}^2 \mathrm{~s}^{-2}$	dose equivalent
katal	$\mathrm{kat}$	$\mathrm{mol} / \mathrm{s}$	$\mathrm{mol} \mathrm{s}^{-1}$	catalytic activity

Table \(\PageIndex{3}\): SI units prefixes.

Prefix	Symbol	Definition	English
yotta-	$\mathrm{Y}$	$10^{24}$	septillion
zetta-	$\mathrm{Z}$	$10^{21}$	sextillion
exa-	$\mathrm{E}$	$10^{18}$	quintillion
peta-	$\mathrm{P}$	$10^{15}$	quadrillion
tera-	$\mathrm{T}$	$10^{12}$	trillion
giga-	$\mathrm{G}$	$10^9$	billion
mega-	$\mathrm{M}$	$10^6$	million
kilo-	$\mathrm{k}$	$10^3$	thousand
hecto-	$\mathrm{h}$	$10^2$	hundred
deka-	$\mathrm{da}$	$10^1$	ten
deci-	$\mathrm{d}$	$10^{-1}$	tenth
centi-	$\mathrm{c}$	$10^{-2}$	hundredth
milli-	$\mathrm{m}$	$10^{-3}$	thousandth
micro-	$\mu$	$10^{-6}$	millionth
nano-	$\mathrm{n}$	$10^{-9}$	billionth
pico-	$\mathrm{p}$	$10^{-12}$	trillionth
femto-	$\mathrm{f}$	$10^{-15}$	quadrillionth
atto-	$\mathrm{a}$	$10^{-18}$	quintillionth
zepto-	$\mathrm{z}$	$10^{-21}$	sextillionth
yocto-	$\mathrm{y}$	$10^{-24}$	septillionth

Table \(\PageIndex{4}\): Prefixes for computer use only

Prefix	Symbol	Definition
yobi-	$\mathrm{Yi}$	$2^{80}$	=1,208,925,819,614,629,174,706,176
zebi-	$\mathrm{Zi}$	$2^{70}$	=1,180,591,620,717,411,303,424
exbi-	$\mathrm{Ei}$	$2^{60}$	=1,152,921,504,606,846,976
pebi-	$\mathrm{Pi}$	$2^{50}$	=1,125,899,906,842,624
tebi-	$\mathrm{Ti}$	$2^{40}$	=1,099,511,627,776
gibi-	$\mathrm{Gi}$	$2^{30}$	=1,073,741,824
mebi-	$\mathrm{Mi}$	$2^{20}$	=1,048,576
kibi-	$\mathrm{Ki}$	$2^{10}$	=1,024