Centimetre

Centimetre
a carpenters' ruler with centimetre divisions
Unit system	metric
Unit of	length
Symbol	cm
1 cm in ...	... is equal to ...
SI units	10 mm
imperial & US system	~0.3937 in

A centimetre (international spelling as used by the International Bureau of Weights and Measures; symbol cm) or centimeter (American spelling) is a unit of length in the metric system, equal to one hundredth of a metre, centi being the SI prefix for a factor of  ¹⁄₁₀₀. The centimetre was the base unit of length in the now deprecated centimetre–gram–second (CGS) system of units.

Though for many physical quantities, SI prefixes for factors of 10³—like milli- and kilo-—are often preferred by technicians, the centimetre remains a practical unit of length for many everyday measurements. A centimetre is approximately the width of the fingernail of an average adult person.

One 1 millilitre is defined as one cubic centimetre, under the SI system of units.

In addition to its use in the measurement of length, the centimetre is used:

For the purposes of compatibility with Chinese, Japanese and Korean (CJK) characters, Unicode has symbols for:

They are mostly used only with East Asian fixed-width CJK fonts, because they are equal in size to one Chinese character.