A millimetre (American spelling: millimeter, symbol mm) is an SI unit of length that is equal to one thousandth of a metre.

1 mm is equal to:

• about 0.03937 inches
• 0.1 cm

The level of rainfall is also reported as millimeters as measured with a rain gauge.

Unicode has symbols for "mm" (㎜), for square millimetre (㎟) and for cubic millimetre (㎣); however, they are useful only with East Asian fixed-width CJK fonts, because they are equal in size to one Chinese character.

micrometre << millimetre << centimetre

See also

• 1 E-3 m
• SI
• SI prefix
• Orders of magnitude