SI Prefixes

International System of Units (SI)

SI Prefixes

Multiples

Factor	Name	Symbol
10²⁴	yotta	Y
10²¹	zetta	Z
10¹⁸	exa	E
10¹⁵	peta	P
10¹²	tera	T
10⁹	giga	G
10⁶	mega	M
10³	kilo	k
10²	hecto	h
10¹	deka	da

	Submultiplies
Factor	Name	Symbol
10⁻¹	deci	d
10⁻²	centi	c
10⁻³	milli	m
10⁻⁶	micro	µ
10⁻⁹	nano	n
10⁻¹²	pico	p
10⁻¹⁵	femto	f
10⁻¹⁸	atto	a
10⁻²¹	zepto	z
10⁻²⁴	yocto	y

Note: The kilogram is the only SI unit with a prefix as part of its name and symbol. Because multiple prefixes are not allowed, the kilogram and prefix names are used with the unit name gram and the prefix symbols are used with the unit symbol g. Other than in this case, any SI prefix may be used with any SI unit, including the degree Celsius and its symbol °C.

Example: 10^–6kg = 1 mg (one milligram),
but not 10^–6 kg = 1 μkg (one microkilogram)

Source: National Institute of Standards and Technology (NIST)