A centimetre (international spelling) or centimeter (American spelling) (SI symbol cm) 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 . 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.

Equivalence to other units of length

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

Other uses

In addition to its use in the measurement of length, the centimetre is used: * sometimes, to report the level of rainfall as measured by a rain gauge * in the CGS system, the centimetre is used to measure capacitance, where 1 cm of capacitance = farads * in maps, centimetres are used to make conversions from map scale to real world scale (kilometres) * to represent second moment of areas (cm4) * as the inverse of the kayser, a CGS unit, and thus a non-SI metric unit of wavenumber: 1 kayser = 1 wave per centimetre; or, more generally, (wavenumber in kaysers) = 1/(wavelength in centimetres). The SI unit of wavenumber is the inverse metre, m−1.

Unicode symbols

For the purposes of compatibility with Chinese, Japanese and Korean (CJK) characters, Unicode has symbols for:CJK Compatibility excerpt
from The Unicode Standard, Version 10.0. * centimetre (㎝) – code 339D * square centimetre (㎠) – code 33A0 * cubic centimetre (㎤) – code 33A4 They are mostly used only with East Asian fixed-width CJK fonts, because they are equal in size to one Chinese character.

See also

*1 E-2 m *Conversion of units, for comparison with other units of length *Reciprocal centimetre *Orders of magnitude (length)


{{Authority control Category:Units of length -02 Category:Centimetre–gram–second system of units Category:SI units Category:100 (number)