Related Resources: Engineering Conversions Equivalent

Decimal Multiples and Submultiples

Engineering Conversions and Equivalents

Decimal Multiples and Submultiples

SI prefixes used to form decimal multiples and submultiples of SI units

Multiple	Prefix	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	deca	da

It is important to note that the kilogram is the only SI unit with a prefix as part of its name and symbol. Because multiple prefixes may not be used, in the case of the kilogram the prefix names of Table 5 are used with the unit name "gram" and the prefix symbols are used with the unit symbol "g." With this exception, any SI prefix may be used with any SI unit, including the degree Celsius and its symbol °C.

 

Example 1:	10-6 kg = 1 mg (one milligram), but not 10-6 kg = 1 µkg (one microkilogram)
Example 2:	Consider the earlier example of the height of the Washington Monument. We may write h W = 169 000 mm = 16 900 cm = 169 m = 0.169 km using the millimeter (SI prefix milli, symbol m), centimeter (SI prefix centi, symbol c), or kilometer (SI prefix kilo, symbol k).

Because the SI prefixes strictly represent powers of 10, they should not be used to represent powers of 2. Thus, one kilobit, or 1 kbit, is 1000 bit and not 2¹⁰ bit = 1024 bit. To alleviate this ambiguity, prefixes for binary multiples have been adopted by the International Electrotechnical Commission (IEC) for use in information technology.

Submultiple	Prefix	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