Picometre

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A picometre (American spelling: picometer, symbol pm) is a unit of length in the metric system, equal to one trillionth (¹/_{1,000,000,000,000}) of a metre, which is the current SI base unit of length. It can be written in scientific notation as 1×10⁻¹² m (engineering notation) or 1 E-12 m (exponential notation) — both meaning 1 m / 1,000,000,000,000.

It equals a millionth of a micrometre (formerly called a micron), and was formerly called micromicron or bicron (and written as µµ^[1]).
It equals a hundredth of an Ångström, an internationally recognized non-SI unit of length.

SI prefixes

Name	yotta-	zetta-	exa-	peta-	tera-	giga-	mega-	kilo-	hecto-	deca-		deci-	centi-	milli-	micro-	nano-	pico-	femto-	atto-	zepto-	yocto-
Symbol	Y	Z	E	P	T	G	M	k	h	da		d	c	m	µ	n	p	f	a	z	y
Factor	1024	1021	1018	1015	1012	109	106	103	102	101	100	10−1	10−2	10−3	10−6	10−9	10−12	10−15	10−18	10−21	10−24

[edit] See also

• 1 E-12 m
• SI
• SI prefix
• Metric system
• Orders of magnitude (length)
• Conversion of units, for comparison with other units of length.

[edit] References

1. ^ How Many? A Dictionary of Units of Measurement; Russ Rowlett and the University of North Carolina at Chapel Hill; http://www.unc.edu/~rowlett/units/dictB.html