A centimetre (American spelling: centimeter, symbol cm) is a unit of length in the metric system, equal to one hundredth of a metre, which is the current SI base unit of length. Centi is the SI prefix for a factor of 10. Hence a centimetre can be written as 10×10 m (engineering notation) or (scientific E notation) — meaning or respectively. The centimetre is the base unit of length in the now deprecated centimetre-gram-second 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 adult person.
The centimeter is the distance light travels through a vacuum in second.
Equivalence to other units of length
1 centimetre is equal
- 0.01 metres, which can be represented by 1.00 E-2 m (1 metre is equal to 100 centimetres)
- about 0.393700787401575 inches (1 inch is equal to 2.54 centimetres exactly)
1 cubic centimetre is equal to 1 millilitre, under the current SI system of units.
Uses of centimetre
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 = 1.113×10 Farad
- in Canadian maps, centimetres are used to make conversions from map scale to real world scale (kilometres)
For the purposes of compatibility with Chinese
) characters, Unicode
has symbols for:
- centimetre (㎝) - code 339D
- square centimetre (㎠) - code 33A0
- cubic centimetre (㎤) - code 33A4
They are useful only with East Asian fixed-width CJK fonts, because they are equal in size to one Chinese character.