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:
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