{{Infobox unit

| name = centimetre

| image = frameless

| caption = A carpenter's ruler with centimetre divisions

| symbol = cm

| standard = SI

| quantity = length

| units1 = millimetres

| inunits1 = 10 mm

| units2 = imperial & US system

| inunits2 = ~

}}

thumb|upright=1.35|Different lengths as in respect to the electromagnetic spectrum, measured by the metre and its derived scales. The microwave is in-between 1 metre to 1 millimetre.

A centimetre (International spelling) or centimeter (American English), with SI symbol cm, is a unit of length in the International System of Units (SI) equal to one hundredth of a metre, centi- being the SI prefix for a factor of . Equivalently, there are 100 centimetres in 1 metre. The centimetre is 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; for instance, human height is commonly measured in centimetres. A centimetre is approximately the width of the fingernail of an average adult person.

Equivalence to other units of length

{|

|-

|rowspan=4 valign=top| centimetre

|= millimetres

|-

|= metres

|-

|= inches (There are exactly 2.54 centimetres in one inch.)

|}

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 –
  • square centimetre –
  • cubic centimetre –

These characters are each equal in size to one Chinese character and are typically used only with East Asian, fixed-width CJK fonts.

See also

  • Conversion of units
  • Orders of magnitude (length)
  • Reciprocal length

References

  • CM to Inch Converter