Millimetre

millimetre
Ruler with millimetre and centimetre marks
General information
Unit system	SI
Unit of	Length
Symbol	mm
Named after	The metric prefix mille (Latin for "one thousand") and the metre
Conversions
1 mm in ...	... is equal to ...
micrometres	1×103 μm = 1000 μm
centimetres	1×10−1 cm = 0.1 cm
metres	1×10−3 m = 0.001 m
kilometres	1×10−6 km
inches	0.039370 in
feet	0.0032808 ft

The millimetre (international spelling; SI unit symbol mm) or millimeter (American spelling) is a unit of length in the International System of Units (SI), equal to one thousandth of a metre, which is the SI base unit of length. Therefore, there are one thousand millimetres in a metre. There are ten millimetres in a centimetre.

One millimetre is equal to 1000 micrometres or 1000000 nanometres. Since an inch is officially defined as exactly 25.4 millimetres, a millimetre is equal to exactly 5⁄127 (≈ 0.03937) of an inch.