SI prefixes: from pico to exa

Kilo is a thousand, mega a million, giga a billion – and on the other side milli, micro, nano. An overview of all common SI prefixes with powers.

Multiples (greater than 1)

Prefix	Symbol	Power	In words	Example
deka	da	10¹	ten	dekagram (10 g)
hecto	h	10²	hundred	hectare, hectopascal
kilo	k	10³	thousand	kilometer, kilogram
mega	M	10⁶	million	megabyte, megawatt
giga	G	10⁹	billion	gigahertz, gigabyte
tera	T	10¹²	trillion	terabyte
peta	P	10¹⁵	quadrillion	petabyte
exa	E	10¹⁸	quintillion	exabyte

Prefix	Symbol	Power	In words	Example
deci	d	10⁻¹	tenth	deciliter
centi	c	10⁻²	hundredth	centimeter
milli	m	10⁻³	thousandth	millimeter, milligram
micro	µ	10⁻⁶	millionth	micrometer, microgram
nano	n	10⁻⁹	billionth	nanometer
pico	p	10⁻¹²	trillionth	picofarad

Beware with data: a kilobyte (kB) is 1,000 B per SI, but a kibibyte (KiB) is 1,024 B – see the data units table.