(SI), equal to , or one trillionth ({{sfrac}})}} of a metre, which is the SI base unit of length.

The picometre is one thousand femtometres, one thousandth of a nanometre ({{sfrac}}}} nm), one millionth of a micrometre (also known as a micron), one billionth of a millimetre, and one trillionth of a metre. The symbol uu was