# Centimetre

Last updated
Centimetre
A carpenter's ruler with centimetre divisions
General information
Unit system metric
Unit of length
Symbolcm
Conversions
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. [1] The centimetre was the base unit of length in the now deprecated centimetre–gram–second (CGS) system of units.

The International Bureau of Weights and Measures is an intergovernmental organization that was established by the Metre Convention, through which member states act together on matters related to measurement science and measurement standards. The organisation is usually referred to by its French initialism, BIPM. The BIPM's secretariat and formal meetings are housed in the organizations headquarters in Sèvres, France.

Length is a measure of distance. In the International System of Quantities, length is any quantity with dimension distance. In most systems of measurement, the unit of length is a base unit, from which other units are derived.

The metric system is an internationally recognised decimalised system of measurement. It is in widespread use, and where it is adopted, it is the only or most common system of weights and measures. It is now known as the International System of Units (SI). It is used to measure everyday things such as the mass of a sack of flour, the height of a person, the speed of a car, and the volume of fuel in its tank. It is also used in science, industry and trade.

## Contents

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

 1 centimetre = 10 millimetres = 0.01 metres = 0.393700787401574803149606299212598425196850 inches (There are exactly 2.54 centimetres in one inch.)

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

The litre or liter is an SI accepted metric system unit of volume equal to 1 cubic decimetre (dm3), 1,000 cubic centimetres (cm3) or 1/1,000 cubic metre. A cubic decimetre occupies a volume of 10 cm×10 cm×10 cm and is thus equal to one-thousandth of a cubic metre.

## 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 [2]
• in the CGS system, the centimetre is used to measure capacitance, where 1 cm of capacitance = 1.113×10−12 farads [3]
• 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.

A rain gauge is an instrument used by meteorologists and hydrologists to gather and measure the amount of liquid precipitation over a set period of time.

Capacitance is the ratio of the change in an electric charge in a system to the corresponding change in its electric potential. There are two closely related notions of capacitance: self capacitance and mutual capacitance. Any object that can be electrically charged exhibits self capacitance. A material with a large self capacitance holds more electric charge at a given voltage than one with low capacitance. The notion of mutual capacitance is particularly important for understanding the operations of the capacitor, one of the three elementary linear electronic components.

The farad is the SI derived unit of electrical capacitance, the ability of a body to store an electrical charge. It is named after the English physicist Michael Faraday.

## Unicode symbols

For the purposes of compatibility with Chinese, Japanese and Korean (CJK) characters, Unicode has symbols for: [4]

Chinese is a group of related, but in many cases not mutually intelligible, language varieties, forming the Sinitic branch of the Sino-Tibetan language family. Chinese is spoken by the ethnic Chinese majority and many minority ethnic groups in China. About 1.2 billion people speak some form of Chinese as their first language.

Japanese is an East Asian language spoken by about 128 million people, primarily in Japan, where it is the national language. It is a member of the Japonic language family, and its relation to other languages, such as Korean, is debated. Japanese has been grouped with language families such as Ainu, Austroasiatic, and the now-discredited Altaic, but none of these proposals has gained widespread acceptance.

Korea is a region in East Asia. Since 1948 it has been divided between two distinct sovereign states, North Korea and South Korea. Korea consists of the Korean Peninsula, Jeju Island, and several minor islands near the peninsula. Korea is bordered by Russia to the northeast, China to the northwest, and Japan to the east via the Korea Strait and the Sea of Japan.

• 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.

## Related Research Articles

The centimetre–gram–second system of units is a variant of the metric system based on the centimetre as the unit of length, the gram as the unit of mass, and the second as the unit of time. All CGS mechanical units are unambiguously derived from these three base units, but there are several different ways of extending the CGS system to cover electromagnetism.

Kilo is a decimal unit prefix in the metric system denoting multiplication by one thousand (103). It is used in the International System of Units where it has the unit symbol k, in lower case.

The micrometre or micrometer, also commonly known by the previous name micron, is an SI derived unit of length equalling 1×10−6 metre ; that is, one millionth of a metre.

The International System of Units is the modern form of the metric system, and is the most widely used system of measurement. It comprises a coherent system of units of measurement built on seven base units, which are the second, metre, kilogram, ampere, kelvin, mole, candela, and a set of twenty prefixes to the unit names and unit symbols that may be used when specifying multiples and fractions of the units. The system also specifies names for 22 derived units, such as lumen and watt, for other common physical quantities.

A metric prefix is a unit prefix that precedes a basic unit of measure to indicate a multiple or fraction of the unit. While all metric prefixes in common use today are decadic, historically there have been a number of binary metric prefixes as well. Each prefix has a unique symbol that is prepended to the unit symbol. The prefix kilo-, for example, may be added to gram to indicate multiplication by one thousand: one kilogram is equal to one thousand grams. The prefix milli-, likewise, may be added to metre to indicate division by one thousand; one millimetre is equal to one thousandth of a metre.

The pascal is the SI derived unit of pressure used to quantify internal pressure, stress, Young's modulus and ultimate tensile strength. It is defined as one newton per square metre. It is named after the French polymath Blaise Pascal.

The millimetre or millimeter is a unit of length in the metric system, equal to one thousandth of a metre, which is the SI base unit of length. Therefore, there are one thousand millimetres in a metre. There are ten millimetres in a centimetre.

A cubic centimetre is a commonly used unit of volume that extends the derived SI-unit cubic metre, and corresponds to the volume of a cube that measures 1 cm × 1 cm × 1 cm. One cubic centimetre corresponds to a volume of 1/1,000,000 of a cubic metre, or 1/1,000 of a litre, or one millilitre; thus, 1 cm3 ≡ 1 mL. The mass of one cubic centimetre of water at 3.98 °C is closely equal to one gram. SI supports only the use of symbols and deprecates the use of any abbreviations for units. Hence cm3 is preferred to cc or ccm.

The square metre or square meter is the SI derived unit of area with symbol m2.

In the physical sciences, the wavenumber is the spatial frequency of a wave, measured in cycles per unit distance or radians per unit distance. Whereas temporal frequency can be thought of as the number of waves per unit time, wavenumber is the number of waves per unit distance.

In the metric system, a microgram or microgramme is a unit of mass equal to one millionth of a gram. The unit symbol is μg according to the International System of Units; the recommended symbol in the United States when communicating medical information is mcg. In μg the prefix symbol for micro- is the Greek letter μ (Mu).

A decametre or dekameter, symbol dam, is a unit of length in the metric system equal to ten metres; it is very rarely used.

The bar is a metric unit of pressure, but is not approved as part of the International System of Units (SI). It is defined as exactly equal to 100,000 Pa, which is slightly less than the current average atmospheric pressure on Earth at sea level.

A unit prefix is a specifier or mnemonic that is prepended to units of measurement to indicate multiples or fractions of the units. Units of various sizes are commonly formed by the use of such prefixes. The prefixes of the metric system, such as kilo and milli, represent multiplication by powers of ten. In information technology it is common to use binary prefixes, which are based on powers of two. Historically, many prefixes have been used or proposed by various sources, but only a narrow set has been recognised by standards organisations.

The ohm is the SI derived unit of electrical resistance, named after German physicist Georg Simon Ohm. Although several empirically derived standard units for expressing electrical resistance were developed in connection with early telegraphy practice, the British Association for the Advancement of Science proposed a unit derived from existing units of mass, length and time and of a convenient size for practical work as early as 1861. The definition of the ohm was revised several times. Today, the definition of the ohm is expressed from the quantum Hall effect.

The MKS system of units is a physical system of measurement that uses the metre, kilogram, and second (MKS) as base units.

The cubic metre or cubic meter is the SI derived unit of volume. Its SI symbol is m3. It is the volume of a cube with edges one metre in length. An alternative name, which allowed a different usage with metric prefixes, was the stère, still sometimes used for dry measure. Another alternative name, no longer widely used, was the kilolitre.

A coherent system of units is a system of units based on a system of quantities in such a way that the equations between the numerical values expressed in the units of the system have exactly the same form, including numerical factors, as the corresponding equations between the quantities. Equivalently, it is a system in which every quantity has a unique unit, or one that does not use conversion factors.

## References

1. "Decimal multiples and submultiples of SI units". Bureau International des Poids et Mesures. 2014. Retrieved 5 July 2015.
2. CJK Compatibility excerpt from The Unicode Standard, Version 10.0.