Metric units are

units Unit may refer to: Arts and entertainment * UNIT, a fictional military organization in the science fiction television series ''Doctor Who'' * Unit of action, a discrete piece of action (or beat) in a theatrical presentation Music * ''Unit'' (al ...

based on the metre, gram or second and decimal (power of ten) multiples or sub-multiples of these. The most widely used examples are the units of the International System of Units (SI). By extension they include units of

electromagnetism In physics, electromagnetism is an interaction that occurs between particles with electric charge. It is the second-strongest of the four fundamental interactions, after the strong force, and it is the dominant force in the interactions of ...

from the CGS and SI units systems, and other units for which use of

SI prefix The International System of Units, known by the international abbreviation SI in all languages and sometimes pleonastically as the SI system, is the modern form of the metric system and the world's most widely used system of measurement. E ...

es has become the norm. Other unit systems using metric units include: *

International System of Electrical and Magnetic Units The International System of Electrical and Magnetic Units is an obsolete system of units used for measuring electrical and magnetic quantities. It was proposed as a system of practical international units by unanimous recommendation at the Internati ...

* Metre–tonne–second (MTS) system of units * MKS system of units (metre, kilogram, second)

Metric units that are part of the SI

The first group of metric units are those that are at present defined as units within the International System of Units (SI). In its most restrictive interpretation, this is what may be meant when the term ''metric unit'' is used. The SI defines 30 named units and associated symbols: * The unit

one 1 (one, unit, unity) is a number representing a single or the only entity. 1 is also a numerical digit and represents a single unit of counting or measurement. For example, a line segment of ''unit length'' is a line segment of length 1. I ...

(1) is the unit of a quantity of dimension one. * The second (s) is the unit of time. * The metre (m) is the unit of length. * The kilogram (kg) is the unit of mass. * The

ampere The ampere (, ; symbol: A), often shortened to amp,SI supports only the use of symbols and deprecates the use of abbreviations for units. is the unit of electric current in the International System of Units (SI). One ampere is equal to elect ...

(A) is the unit of electric current. * The kelvin (K) is the unit of

thermodynamic temperature Thermodynamic temperature is a quantity defined in thermodynamics as distinct from kinetic theory or statistical mechanics. Historically, thermodynamic temperature was defined by Kelvin in terms of a macroscopic relation between thermodynamic w ...

. * The

mole Mole (or Molé) may refer to: Animals * Mole (animal) or "true mole", mammals in the family Talpidae, found in Eurasia and North America * Golden moles, southern African mammals in the family Chrysochloridae, similar to but unrelated to Talpida ...

(mol) is the unit of

amount of substance In chemistry, the amount of substance ''n'' in a given sample of matter is defined as the quantity or number of discrete atomic-scale particles in it divided by the Avogadro constant ''N''A. The particles or entities may be molecules, atoms, ions, ...

. * The

candela The candela ( or ; symbol: cd) is the unit of luminous intensity in the International System of Units (SI). It measures luminous power per unit solid angle emitted by a light source in a particular direction. Luminous intensity is analogous to ...

(cd) is the unit of luminous intensity. * The hertz (Hz) is equal to one reciprocal second (). * The radian (rad) is equal to one (). * The steradian (sr) is equal to one (). * The newton (N) is equal to one kilogram-metre per second squared (). * The

pascal Pascal, Pascal's or PASCAL may refer to: People and fictional characters * Pascal (given name), including a list of people with the name * Pascal (surname), including a list of people and fictional characters with the name ** Blaise Pascal, Frenc ...

(Pa) is equal to one newton per square metre (). * The joule (J) is equal to one newton-metre (). * The watt (W) is equal to one joule per second (). * The coulomb (C) is equal to one ampere second (). * The volt (V) is equal to one joule per coulomb (). * The

weber Weber (, or ; German: ) is a surname of German origin, derived from the noun meaning " weaver". In some cases, following migration to English-speaking countries, it has been anglicised to the English surname 'Webber' or even 'Weaver'. Notable pe ...

(Wb) is equal to one volt-second (). * The tesla (T) is equal to one weber per square metre (). * The farad (F) is equal to one coulomb per volt (). * The

ohm Ohm (symbol Ω) is a unit of electrical resistance named after Georg Ohm. Ohm or OHM may also refer to: People * Georg Ohm (1789–1854), German physicist and namesake of the term ''ohm'' * Germán Ohm (born 1936), Mexican boxer * Jörg Ohm (bor ...

(Ω) is equal to one volt per ampere (). * The siemens (S) is equal to one ampere per volt (). * The henry (H) is equal to one volt-second per ampere (). * The

degree Celsius Degree may refer to: As a unit of measurement * Degree (angle), a unit of angle measurement ** Degree of geographical latitude ** Degree of geographical longitude * Degree symbol (°), a notation used in science, engineering, and mathematics ...

(°C) is equal to one kelvin (). * The lumen (lm) is equal to one candela-steradian (). * The

lux The lux (symbol: lx) is the unit of illuminance, or luminous flux per unit area, in the International System of Units (SI). It is equal to one lumen per square metre. In photometry, this is used as a measure of the intensity, as perceived by ...

(lx) is equal to one lumen per square metre (). * The

becquerel The becquerel (; symbol: Bq) is the unit of radioactivity in the International System of Units (SI). One becquerel is defined as the activity of a quantity of radioactive material in which one nucleus decays per second. For applications relatin ...

(Bq) is equal to one reciprocal second (). * The

gray Grey (more common in British English) or gray (more common in American English) is an intermediate color between black and white. It is a neutral or achromatic color, meaning literally that it is "without color", because it can be composed ...

(Gy) is equal to one joule per kilogram (). * The sievert (Sv) is equal to one joule per kilogram (). * The

katal The katal (symbol: kat) is the unit of catalytic activity in the International System of Units (SI) used for quantifying the catalytic activity of enzymes (that is, measuring the enzymatic activity level in enzyme catalysis) and other catalyst ...

(kat) is equal to one mole per second (). There are twenty-four metric prefixes that can be combined with any of these units except one (1) and kilogram (kg) to form further units of the SI. For mass, the same prefixes are applied to the gram (g) instead of the kilogram.

Metric units that are not part of the SI

There are several metric systems, most of which have become disused or are still used in only niche disciplines. Systems are listed with named units that are associated with them.

CGS

The

centimetre–gram–second system of units The centimetre–gram–second system of units (abbreviated CGS or cgs) 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 a ...

(CGS) is based on three base units: centimetre, gram and second. Its subsystems ( CGS-ESU, CGS-EMU and CGS-Gaussian) have different defining equations for their systems of quantities for defining electromagnetic quantities and hence the associated units, with CGS-Gaussian units being selected from each of the other two subsystems. The CGS-to-SI correspondence of electromagnetic units as given was exact prior to the

2019 redefinition of the SI base units In 2019, four of the seven SI base units specified in the International System of Quantities were redefined in terms of natural physical constants, rather than human artifacts such as the standard kilogram. Effective 20 May 2019, the 144th ...

, until which the magnetic constant ''μ''₀ was defined as . As from the redefinition, ''μ''₀ has an inexactly known value when expressed in SI units, with the exactness of the electromagnetic unit correspondence given here being affected accordingly.

CGS nonelectromagnetic units

* The kayser (K) is a unit of wavenumber equal to (). * The gal (Gal) is a unit of

acceleration In mechanics, acceleration is the rate of change of the velocity of an object with respect to time. Accelerations are vector quantities (in that they have magnitude and direction). The orientation of an object's acceleration is given by the ...

equal to . * The dyne (dyn) is a unit of force equal to (). * The

barye The barye (symbol: Ba), or sometimes barad, barrie, bary, baryd, baryed, or barie, is the centimetre–gram–second (CGS) unit of pressure. It is equal to 1 dyne per square centimetre. : = = = = = See also *Pas ...

(Ba) is a unit of pressure equal to (). * The

erg The erg is a unit of energy equal to 10−7joules (100 nJ). It originated in the Centimetre–gram–second system of units (CGS). It has the symbol ''erg''. The erg is not an SI unit. Its name is derived from (), a Greek word meaning 'work' o ...

(erg) is a unit of energy equal to (). * The poise (P) is a unit of dynamic viscosity equal to (). * The stokes (St) is a unit of kinematic viscosity equal to (). * The stilb (sb) is a unit of luminance equal to (). * The

phot A phot (ph) is a photometric unit of illuminance, or luminous flux through an area. It is not an SI unit but rather is associated with the older centimetre–gram–second system of units. The name was coined by André Blondel in 1921.Parry Moon ...

(ph) is a unit of illuminance equal to (). * The

rayl A Rayl, rayl or Rayleigh is one of two units of specific acoustic impedance or, equivalently, characteristic acoustic impedance; one an MKS unit, and the other a CGS unit. These have the same dimensions as momentum per volume. The units are na ...

is a unit of

specific acoustic impedance Acoustic impedance and specific acoustic impedance are measures of the opposition that a system presents to the acoustic flow resulting from an acoustic pressure applied to the system. The SI unit of acoustic impedance is the pascal-second per cub ...

, equal to 1 dyn⋅s⋅cm⁻³.

CGS-ESU electromagnetic units

* The statwatt (statW) is a unit of

power Power most often refers to: * Power (physics), meaning "rate of doing work" ** Engine power, the power put out by an engine ** Electric power * Power (social and political), the ability to influence people or events ** Abusive power Power may ...

equal to , which is equal to . * The

statcoulomb The franklin (Fr) or statcoulomb (statC) electrostatic unit of charge (esu) is the physical unit for electrical charge used in the cgs-esu and Gaussian units. It is a derived unit given by : 1 statC = 1 dyn1/2⋅cm = 1 cm3/2⋅g1/2⋅s−1. That ...

(statC) or

franklin Franklin may refer to: People * Franklin (given name) * Franklin (surname) * Franklin (class), a member of a historical English social class Places Australia * Franklin, Tasmania, a township * Division of Franklin, federal electoral d ...

(Fr) is a unit of electric charge equal to , corresponding to ~. * The statampere (statA) is a unit of electric current equal to , corresponding to ~. * The

statvolt The statvolt is a unit of voltage and electrical potential used in the CGS-ESU and gaussian systems of units. In terms of its relation to the SI units, one statvolt corresponds to exactly , i.e. to 299.792458 volts. The statvolt is also ...

(statV) is a unit of electric potential difference equal to , corresponding to . * The

statohm The statohm is the unit of electrical resistance in the electrostatic system of units which was part of the CGS system of units based upon the centimetre, gram and second. The static units in that system were related to the equivalent electromagn ...

is a unit of electric resistance equal to , corresponding to ~. * The statsiemens or statmho is a unit of

electric conductance The electrical resistance of an object is a measure of its opposition to the flow of electric current. Its reciprocal quantity is , measuring the ease with which an electric current passes. Electrical resistance shares some conceptual parallel ...

equal to , corresponding to ~. * The stathenry is a unit of electric inductance equal to , corresponding to ~. * The statfarad (statF) is a unit of electric capacitance equal to , corresponding to ~. * The statdaraf (statD) is a unit of electric elastance equal to 1/statF. * The statweber is a unit of

magnetic flux In physics, specifically electromagnetism, the magnetic flux through a surface is the surface integral of the normal component of the magnetic field B over that surface. It is usually denoted or . The SI unit of magnetic flux is the weber ...

, corresponding to . * The stattesla is a unit of

magnetic flux density A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to ...

equal to , corresponding to .

CGS-EMU electromagnetic units

* The abwatt (abW) is a unit of

equal to , which is equal to . * The

abcoulomb The abcoulomb (abC or aC) or electromagnetic unit of charge (emu of charge) is the derived physical unit of electric charge in the cgs-emu system of units. One abcoulomb is equal to ten coulombs. The name "abcoulomb" was introduced by Kennell ...

(abC) is a unit of electric charge equal to , corresponding to . * The

abampere The abampere (abA), also called the biot (Bi) after Jean-Baptiste Biot, is the derived electromagnetic unit of electric current in the emu-cgs system of units (electromagnetic cgs). One abampere corresponds to ten amperes in the SI system of ...

(abA) or biot (Bi) is a unit of electric current, corresponding to . * The

abvolt The abvolt (abV) is the unit of potential difference in the CGS-EMU system of units. It corresponds to in the SI system and 1/ statvolt ≈ in the CGS-ESU system. A potential difference of 1 abV will drive a current of one abampere through ...

(abV) is a unit of electric potential difference, corresponding to . * The

abohm The abohm is the derived unit of electrical resistance in the emu-cgs ''(centimeter-gram-second)'' system of units (emu stands for "electromagnetic units"). One abohm corresponds to 10−9 ohms in the SI system of units, which is a nanooh ...

(abΩ) is a unit of electric resistance, corresponding to . * The abmho is a unit of

, corresponding to . * The abhenry is a unit of electric inductance, corresponding to . * The abfarad (abF) is a unit of electric capacitance, corresponding to . * The

gilbert Gilbert may refer to: People and fictional characters *Gilbert (given name), including a list of people and fictional characters *Gilbert (surname), including a list of people Places Australia * Gilbert River (Queensland) * Gilbert River (South A ...

(Gb) is a unit of magnetomotive force equal to one biot-turn, corresponding to (10/4π) A = . * The oersted (Oe) is a unit of magnetic field strength equal to , corresponding to (1000/4π) A/m = . * The

maxwell Maxwell may refer to: People * Maxwell (surname), including a list of people and fictional characters with the name ** James Clerk Maxwell, mathematician and physicist * Justice Maxwell (disambiguation) * Maxwell baronets, in the Baronetage of ...

(Mx) is a unit of

, corresponding to . * The

gauss Johann Carl Friedrich Gauss (; german: Gauß ; la, Carolus Fridericus Gauss; 30 April 177723 February 1855) was a German mathematician and physicist who made significant contributions to many fields in mathematics and science. Sometimes refer ...

(G) is a unit of

, corresponding to .

CGS-Gaussian electromagnetic units

* The

(Fr) is a unit of electric charge equal to , corresponding to ~. * The oersted (Oe) is a unit of magnetic field strength equal to , corresponding to ~. * The

(Mx) is a unit of

, corresponding to . * The

(G) is a unit of

, corresponding to .

MTS

* The tonne (t) is a unit of mass equal to . * The sthène (sn) is a unit of force equal to . * The

pièze The pièze () is the unit of pressure in the metre–tonne–second system of units (mts system), used, e.g., in the former Soviet Union 1933–1955. It is defined as one sthène per square metre The square metre ( international spelling as use ...

(pz) is a unit of pressure equal to .

MKSA

* The

cycle per second The cycle per second is a once-common English name for the unit of frequency now known as the hertz (Hz). The plural form was typically used, often written cycles per second, cycles/second, c.p.s., c/s, or, ambiguously, just cycles (Cy./Cyc.). The ...

(cps or cyc/s) is a unit of frequency equal to . * The MKS

is a unit of

acoustic impedance Acoustic impedance and specific acoustic impedance are measures of the opposition that a system presents to the acoustic flow resulting from an acoustic pressure applied to the system. The SI unit of acoustic impedance is the pascal-second per cu ...

equal to . * The

mho The siemens (symbol: S) is the unit of electric conductance, electric susceptance, and electric admittance in the International System of Units (SI). Conductance, susceptance, and admittance are the reciprocals of resistance, reactance, and ...

(℧) is a unit of

equal to .

MKpS units

* The

kilogram-force The kilogram-force (kgf or kgF), or kilopond (kp, from la, pondus, lit=weight), is a non-standard gravitational metric unit of force. It does not comply with the International System of Units (SI) and is deprecated for most uses. The kilogram-f ...

(kgf), also

kilopond The kilogram-force (kgf or kgF), or kilopond (kp, from la, pondus, lit=weight), is a non-standard gravitational metric unit of force. It does not comply with the International System of Units (SI) and is deprecated for most uses. The kilogram-f ...

(kp), is a unit of force (). * The hyl is a unit of mass equal to (). * The poncelet (p) is a unit of

equal to (). * The technical atmosphere (at) is a (non-coherent) unit of pressure equal to ().

Other metric units

Length

* The

fermi Enrico Fermi (; 29 September 1901 – 28 November 1954) was an Italian (later naturalized American) physicist and the creator of the world's first nuclear reactor, the Chicago Pile-1. He has been called the "architect of the nuclear age" and t ...

is a unit of distance used in nuclear physics equal to . * The

angstrom The angstromEntry "angstrom" in the Oxford online dictionary. Retrieved on 2019-03-02 from https://en.oxforddictionaries.com/definition/angstrom.Entry "angstrom" in the Merriam-Webster online dictionary. Retrieved on 2019-03-02 from https://www.m ...

(symbol Å) is a unit of distance used in chemistry and

atomic physics Atomic physics is the field of physics that studies atoms as an isolated system of electrons and an atomic nucleus. Atomic physics typically refers to the study of atomic structure and the interaction between atoms. It is primarily concerned w ...

equal to . * The

micron The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer ( American spelling), also commonly known as a micron, is a unit of length in the International System of Un ...

(μ) is a unit of distance equal to one micrometre (). * The basic module (M) is a unit of distance equal to one hundred millimetres (). * The

myriametre The following are examples of orders of magnitude for different lengths. __TOC__ Overview Detailed list To help compare different orders of magnitude, the following list describes various lengths between 1.6 \times 10^ metres and 10^ ...

(mym) is a unit of distance equal to ten kilometres (). * The hebdometre is a unit of distance equal to ten megametres (). * The spat (S) is a unit of distance equal to one

terametre The following are examples of orders of magnitude for different lengths. __TOC__ Overview Detailed list To help compare different orders of magnitude, the following list describes various lengths between 1.6 \times 10^ metres and 10^ ...

().

Area

* The shed is a unit of area used in nuclear physics equal to 10⁻²⁴

barn A barn is an agricultural building usually on farms and used for various purposes. In North America, a barn refers to structures that house livestock, including cattle and horses, as well as equipment and fodder, and often grain.Allen G. N ...

s (100 rm² = 10⁻⁵² m²). * The outhouse is a unit of area used in nuclear physics equal to 10⁻⁶ barns (100 am² = 10⁻³⁴ m²). * The

(b) is a unit of area used in nuclear physics equal to one hundred femtometres squared (100 fm² = 10⁻²⁸ m²). * The

are Are commonly refers to: * Are (unit), a unit of area equal to 100 m2 Are, ARE or Åre may also refer to: Places * Åre, a locality in Sweden * Åre Municipality, a municipality in Sweden ** Åre ski resort in Sweden * Are Parish, a munici ...

(a) is a unit of area equal to . * The decare (daa) is a unit of area equal to . * The hectare (ha) is a unit of area equal to .

Volume

* The lambda (λ) is a unit of volume equal to one cubic

millimetre file:EM Spectrum Properties edit.svg, 330px, Different lengths as in respect to the electromagnetic spectrum, measured by the metre and its derived scales. The microwave is between 1 meter to 1 millimeter. The millimetre (American and British Eng ...

(1 mm³). * The

litre The litre (international spelling) or liter (American English spelling) (SI symbols L and l, other symbol used: ℓ) is a metric unit of volume. It is equal to 1 cubic decimetre (dm3), 1000 cubic centimetres (cm3) or 0.001 cubic metre (m3) ...

(symbol l or L) is a unit of volume equal to one cubic

decimetre The decimetre (symbol dm) or decimeter (American English) is a unit of length in the International System of Units (SI), equal to one tenth of a metre, ten centimetres, 100 millimetres or 3.937 inches. The common non-SI metric unit of volume ...

(1 dm³). * The stere (st) is a unit of volume equal to .

Reciprocal length

* The dioptre is a unit of optical power equal to one

reciprocal metre Reciprocal length or inverse length is a quantity or measurement used in several branches of science and mathematics. As the reciprocal of length, common units used for this measurement include the reciprocal metre or inverse metre (symbol: m&minu ...

().

Time

* The

svedberg A Svedberg unit or svedberg (symbol S, sometimes Sv) is a non- SI metric unit for sedimentation coefficients. The Svedberg unit offers a measure of a particle's size indirectly based on its sedimentation rate under acceleration (i.e. how fast a ...

(S or Sv) is a unit of time used in chemistry equal to one hundred femtoseconds (). * The shake is a unit of time used in nuclear physics equal to ten nanoseconds (). * The sigma is a unit of time equal to one microsecond (). * The jiffy is sometimes used to mean a unit of time of .

Reciprocal time

* The

fresnel Augustin-Jean Fresnel (10 May 1788 – 14 July 1827) was a French civil engineer and physicist whose research in optics led to the almost unanimous acceptance of the wave theory of light, excluding any remnant of Newton's corpuscular th ...

is a unit of frequency equal to .

Reciprocal time squared

* The eotvos (E) is a unit of gravitational gradient equal to ().

Speed

* The benz is a unit of speed equal to one metre per second (1 m/s).

Acceleration

* The leo is a unit of acceleration equal to .

Flow rate

* The sverdrup (Sv) is a unit of volume flow rate equal to one million metres cubed per second (10⁶ m³/s).Aldersey-Williams, 2016
/ref>

Mass

* The undecimogramme is a unit of mass equal to ten picograms (10 pg). * The gamma (γ) is a unit of mass equal to one microgram (1 μg). * The gravet is a unit of mass equal to one gram (1 g). * The

grave A grave is a location where a dead body (typically that of a human, although sometimes that of an animal) is buried or interred after a funeral. Graves are usually located in special areas set aside for the purpose of burial, such as gravey ...

is a unit of mass equal to one kilogram (1 kg). * The

bar Bar or BAR may refer to: Food and drink * Bar (establishment), selling alcoholic beverages * Candy bar * Chocolate bar Science and technology * Bar (river morphology), a deposit of sediment * Bar (tropical cyclone), a layer of cloud * Bar ( ...

is a unit of mass equal to one megagram (1 Mg).

Linear mass density

* The

tex Tex may refer to: People and fictional characters * Tex (nickname), a list of people and fictional characters with the nickname * Joe Tex (1933–1982), stage name of American soul singer Joseph Arrington Jr. Entertainment * ''Tex'', the Italian ...

(tex) is a unit of

linear mass density Linear density is the measure of a quantity of any characteristic value per unit of length. Linear mass density (titer in textile engineering, the amount of mass per unit length) and linear charge density (the amount of electric charge per unit ...

equal to one gram per kilometre (1 g/km). * The number metric (Nm) is equal to 1000 metres per kilogram (1 km/kg).

Pressure

* The

metre sea water The metre (or meter) sea water (msw) is a metric unit of pressure used in underwater diving. It is defined as one tenth of a bar. The unit used in the US is the foot sea water (fsw), based on standard gravity and a sea-water density of 64&nb ...

(msw) is a unit of pressure defined as 0.1

, which is equal to . * The bar (bar) is a unit of pressure equal to .

Energy

* The foe is a unit of energy equal to ().

Viscosity

* The poiseuille is a unit of dynamic viscosity equal to one pascal-second ().

Electrical

* The

Siemens mercury unit The Siemens mercury unit is an obsolete unit of electrical resistance. It was defined by Werner von Siemens in 1860 as the resistance of a mercury column with a length of one metre and uniform cross-section of held at a temperature of zero d ...

is a unit of electric resistance, corresponding to ~. * The gamma (γ) a unit of

, corresponding to . * The debye (D) is a unit of electric dipole moment equal to , corresponding to ~. * The

buckingham Buckingham ( ) is a market town in north Buckinghamshire, England, close to the borders of Northamptonshire and Oxfordshire, which had a population of 12,890 at the 2011 Census. The town lies approximately west of Central Milton Keynes, sou ...

(B) is a unit of electric

quadrupole moment A quadrupole or quadrapole is one of a sequence of configurations of things like electric charge or current, or gravitational mass that can exist in ideal form, but it is usually just part of a multipole expansion of a more complex structure ref ...

equal to .

Electromagnetic radiation

* The jansky (Jy) is a unit of

spectral irradiance In radiometry, irradiance is the radiant flux ''received'' by a ''surface'' per unit area. The SI unit of irradiance is the watt per square metre (W⋅m−2). The CGS unit erg per square centimetre per second (erg⋅cm−2⋅s−1) is often use ...

equal to 10⁻²⁶ W⋅m⁻²⋅Hz⁻¹ (). * The

solar flux unit The solar flux unit (sfu) is a convenient measure of spectral flux density often used in solar radio observations, such as the F10.7 solar activity index: :1 sfu = 104 Jy = 10−22 W⋅m−2⋅Hz−1 = 10−19 erg⋅s−1⋅cm−2⋅Hz� ...

is a unit of

equal to 10⁻²² W⋅m⁻²⋅Hz⁻¹ (). * The nox (nx) is a unit of illuminance equal to 1 millilux (). * The nit (nt) is a unit of luminance equal to one

per metre squared (). * The lambert (L) is a unit of luminance equal to 10⁴/π cd⋅m⁻². * The lumerg is a unit of

luminous energy In photometry, luminous energy is the perceived energy of light. This is sometimes called the quantity of light.talbot Talbot was an automobile marque introduced in 1902 by English-French company Clément-Talbot. The founders, Charles Chetwynd-Talbot, 20th Earl of Shrewsbury and Adolphe Clément-Bayard, reduced their financial interests in their Clément-Talbot ...

(T) is a unit of

luminous energy In photometry, luminous energy is the perceived energy of light. This is sometimes called the quantity of light.einstein (E) is a unit of

amount Quantity or amount is a property that can exist as a multitude or magnitude, which illustrate discontinuity and continuity. Quantities can be compared in terms of "more", "less", or "equal", or by assigning a numerical value multiple of a un ...

of photons, equal to one

(1 mol) of photons. * The rayleigh (R) is a unit of photon flux rate density equal to 10¹⁰ m⁻²⋅s⁻¹ (10⁴ mm⁻²⋅s⁻¹).

Radioactivity

* The rad (rad) is a unit of

absorbed dose Absorbed dose is a dose quantity which is the measure of the energy deposited in matter by ionizing radiation per unit mass. Absorbed dose is used in the calculation of dose uptake in living tissue in both radiation protection (reduction of harm ...

equal to . * The roentgen equivalent man (rem) is a unit of equivalent dose equal to . * The rutherford (Rd) is a unit of radioactivity defined as one million decays per second ().

Concentration

* The molar (M) is equal to one mole per litre ().

Nonmetric units

Hybrid units

Some nonmetric units arose as a combination of a nonmetric quantity combined with a metric unit. Examples include:

Metric unit combined with a unit permitted alongside the SI

* The

ampere hour An ampere hour or amp hour (symbol: A⋅h or A h; often simplified as Ah) is a unit of electric charge, having dimensions of electric current multiplied by time, equal to the charge transferred by a steady current of one ampere flowing for o ...

is a unit of electric charge equal to . * The

watt hour A kilowatt-hour ( unit symbol: kW⋅h or kW h; commonly written as kWh) is a unit of energy: one kilowatt of power for one hour. In terms of SI derived units with special names, it equals 3.6 megajoules (MJ). Kilowatt-hours are a common bil ...

(W⋅h) is equal to . * The watt hour per day (W⋅h/d) is a unit of power equal to 3.6 kJ/(24 h) = 1/24 W. * The

enzyme unit The enzyme unit, or international unit for enzyme (symbol U, sometimes also IU) is a unit of enzyme's catalytic activity. 1 U (μmol/min) is defined as the amount of the enzyme that catalyzes the conversion of one micro mole of substrate per mi ...

(U) is equal to one micromole per minute (50/3 nkat).

Other combinations

* The normal litre per minute (NLPM) is approximately equal to (0.001/60) m³/s. * The

standard litre per minute The standard liter per minute (SLM or SLPM) is a unit of volumetric flow rate of a gas at standard conditions for temperature and pressure (STP), which is most commonly practiced in the United States, whereas European practice revolves around th ...

(SLPM) is approximately equal to (0.001/60) m³/s. * The

centimetre of water A centimetre or millimetre of water (US spelling ''centimeter'' or ''millimeter of water'') are less commonly used measures of pressure derived from pressure head. Centimetre of water A ''centimetre of water'' (US spelling ''centimeter of water ...

(cmH₂O) is approximately . * The millimetre of mercury (mmHg) is approximately . * The torr (Torr) is approximately 133.3224 pascals. * The centimetre of mercury (cmHg) is approximately . * The electronvolt (eV) is equal to = . * The

calorie The calorie is a unit of energy. For historical reasons, two main definitions of "calorie" are in wide use. The large calorie, food calorie, or kilogram calorie was originally defined as the amount of heat needed to raise the temperature of on ...

(cal) is . * The

langley Langley may refer to: People * Langley (surname), a common English surname, including a list of notable people with the name * Dawn Langley Simmons (1922–2000), English author and biographer * Elizabeth Langley (born 1933), Canadian perfor ...

(Ly) is a unit of energy density equal to 1 calorie per square centimetre (). * The darcy (d) is a unit of permeability approximately equal to ().

Traditional units standardized in terms of metric units

Further traditional units were standardized by defining them in terms of metric units, such as the imperial inch, almost always retaining their original name, and replaced the units as traditionally defined. Nonmetric units that arose as approximations to traditional units that were adjusted for convenient conversion to metric units were typically named as for the traditional unit but qualified with the word "metric". The corresponding original traditional usually remained in use alongside the corresponding "metric" version.

Units equal to an SI unit multiplied by an integer power of 10, and multiplied or divided by 1, 2, 3 or 4

* The neper (Np) is a unit of logarithmic ratio equal to 1. * The

percent In mathematics, a percentage (from la, per centum, "by a hundred") is a number or ratio expressed as a fraction of 100. It is often denoted using the percent sign, "%", although the abbreviations "pct.", "pct" and sometimes "pc" are also u ...

(%) is equal to one part in a hundred (0.01). * The

permille Per mille (from Latin , "in each thousand") is an expression that means parts per thousand. Other recognised spellings include per mil, per mill, permil, permill, or permille. The associated sign is written , which looks like a percent sig ...

(‰) is equal to one part in a thousand (0.001). * The

permyriad A basis point (often abbreviated as bp, often pronounced as "bip" or "beep") is one hundredth of 1 percentage point. The related term '' permyriad'' means one hundredth of 1 percent. Changes of interest rates are often stated in basis points. If ...

(‱) is equal to one part in ten thousand (). * The part per million (ppm) is equal to one part in a million (). * The part per billion (ppb) is equal to one part in a billion (). * The

part per trillion In science and engineering, the parts-per notation is a set of pseudo-units to describe small values of miscellaneous dimensionless quantities, e.g. mole fraction or mass fraction. Since these fractions are quantity-per-quantity measures, they ...

(ppt) is equal to one part in a trillion (). * The part per quadrillion (ppq) is equal to one part in a quadrillion (). * The metric inch is equal to twenty five

s (). * The cun is equal to one tenth of a

chi Chi or CHI may refer to: Greek *Chi (letter), the Greek letter (uppercase Χ, lowercase χ); Chinese * ''Chi'' (length) (尺), a traditional unit of length, about ⅓ meter * Chi (mythology) (螭), a dragon *Chi (surname) (池, pinyin: ''chí' ...

(approximately 33.3333 mm). * The

metric foot ISO 2848 (''Building construction – Modular coordination – Principles and rules)'' is an international standard for the construction industry that describes the aims of modular coordination and gives the rules to be used in establishing the di ...

is equal to three hundred millimetres (). * The chi is equal to one third of a metre (approximately 333.333 mm). * The metric lieue is equal to four kilometres (). * The

Scandinavian mile A Scandinavian mile ( Norwegian and sv, mil, [], like "meal") is a unit of length common in Norway and Sweden, but not Denmark. Today, it is standardised as 1 being , but it had different values in the past. The word is derived from the same ...

(''mil'') is equal to ten kilometres (). * The metric dunam is equal to one thousand metres squared (). * The

stremma The stremma ( stremmata; el, στρέμμα, ''strémma'') is a Greek unit of land area equal to 1,000 square metres. Historically, stremmata were not standardized, and may have been anywhere from . History The ancient Greek equivalent was the s ...

is equal to one thousand metres squared (1000 m²). * The '' food labeling ounce'' is equal to 30 cm³. * The

metric cup The cup is a cooking measure of volume, commonly associated with cooking and serving sizes. In the US, it is traditionally equal to . Because actual drinking cups may differ greatly from the size of this unit, standard measuring cups may be used ...

is equal to . * The metric carat (ct) is equal to . * The li is equal to one ten-thousandth of a jin (50 mg). * The

fen A fen is a type of peat-accumulating wetland fed by mineral-rich ground or surface water. It is one of the main types of wetlands along with marshes, swamps, and bogs. Bogs and fens, both peat-forming ecosystems, are also known as mires ...

is equal to one thousandth of a jin (500 mg). * The qian is equal to one hundredth of a jin (5 g). * The liang (or tael) is equal to one tenth of a jin (50 g). * The metric pound is equal to . * The jin (or catty) is equal to 500 g. * The dan is equal to one hundred jin (50 kg). * The metric quintal (q) is equal to one hundred kilograms (). * The donkey power is equal to 250 W.

Other units

* The mo is equal to one ten-thousandth of a

shaku Shaku may refer to: * Shaku (unit) * Shaku (ritual baton) * Buddhist surname In East Asian Buddhism, monks and nuns usually adopt a Buddhist surname and a Dharma name, which are combined in the surname-first East-Asian naming order. Since the 4th ...

(approximately 0.0303030 mm). * The rin is equal to one thousandth of a shaku (approximately 0.303030 mm). * The bu is equal to one hundredth of a shaku (approximately 3.03030 mm). * The

sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...

is equal to one tenth of a shaku (approximately 30.3030 mm). * The

is equal to 10/33 m (approximately 303.030 mm). * The jo is equal to ten shaku (approximately 3030.30 mm). * The metric mile is equal to . * The

tsubo A ''pyeong'' (abbreviationpy) is a Korean unit of area and floorspace, equal to a square '' kan'' or 36square Korean feet. The ''ping'' and ''tsubo'' are its equivalent Taiwanese and Japanese units, similarly based on a square '' bu'' ( ja:步 ...

is equal to 400/121 metres squared (approximately 3.306 m²). * The sho is equal to 2401/1331 litres (approximately 1.804 dm³). * The hyakume is equal to one tenth of a kan (375 g). * The kan is equal to 15/4 kilograms (3.75 kg). * The

metric horsepower Horsepower (hp) is a unit of measurement of power, or the rate at which work is done, usually in reference to the output of engines or motors. There are many different standards and types of horsepower. Two common definitions used today are the ...

is equal to (approximately 735.499 W).

Notes

References

{{Reflist Metric system