Millimetre (mm)

Length

6.21×10⁻⁷ mi

A millimetre (American spelling: millimeter, symbol mm) is one thousandth of a metre (the metre is the International System of Units (SI) base unit of length). The millimetre is part of a metric system. The corresponding unit of area is the square millimetre and the corresponding unit of volume is the cubic millimetre.

Metric

British/American

Nautical

Astronomical