Picometre

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

femtometre &lt;&lt;&lt; picometre &lt;&lt;&lt; nanometre &lt;&lt;&lt; micrometre &lt;&lt;&lt; millimetre &lt; centimetre &lt; decimetre &lt; metre &lt; decametre &lt; hectometre &lt; kilometre

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