Metric units are units 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 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. ...

(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 o ...

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. ...

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 The MKS system of units is a physical system of measurement that uses the metre, kilogram, and second (MKS) as base units. It forms the base of the International System of Units (SI), though SI has since been redefined by different fundament ...

(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 A dimensionless quantity (also known as a bare quantity, pure quantity, or scalar quantity as well as quantity of dimension one) is a quantity to which no physical dimension is assigned, with a corresponding SI unit of measurement of one (or ...

. * The

second The second (symbol: s) is the unit of time in the International System of Units (SI), historically defined as of a day – this factor derived from the division of the day first into 24 hours, then to 60 minutes and finally to 60 seconds ea ...

(s) is the unit of

time Time is the continued sequence of existence and event (philosophy), events that occurs in an apparently irreversible process, irreversible succession from the past, through the present, into the future. It is a component quantity of various me ...

. * The

metre The metre ( British spelling) or meter ( American spelling; see spelling differences) (from the French unit , from the Greek noun , "measure"), symbol m, is the primary unit of length in the International System of Units (SI), though its pre ...

(m) is the unit of

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

. * The

kilogram The kilogram (also kilogramme) is the unit of mass in the International System of Units (SI), having the unit symbol kg. It is a widely used measure in science, engineering and commerce worldwide, and is often simply called a kilo colloquially. ...

(kg) is the unit of

mass Mass is an intrinsic property of a body. It was traditionally believed to be related to the quantity of matter in a physical body, until the discovery of the atom and particle physics. It was found that different atoms and different ele ...

. * 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 An electric current is a stream of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is measured as the net rate of flow of electric charge through a surface or into a control volume. The movi ...

. * The

kelvin The kelvin, symbol K, is the primary unit of temperature in the International System of Units (SI), used alongside its prefixed forms and the degree Celsius. It is named after the Belfast-born and University of Glasgow-based engineer and ...

(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 ...

. * The mole (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, io ...

. * 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 t ...

(cd) is the unit of

luminous intensity In photometry, luminous intensity is a measure of the wavelength-weighted power emitted by a light source in a particular direction per unit solid angle, based on the luminosity function, a standardized model of the sensitivity of the human e ...

. * The

hertz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that o ...

(Hz) is equal to one

reciprocal second The inverse second or reciprocal second (s−1) is a unit of frequency, defined as the multiplicative inverse of the second (a unit of time). It is dimensionally equivalent to: * the unit hertz – the SI unit for frequency * the unit radian per s ...

(). * The

radian The radian, denoted by the symbol rad, is the unit of angle in the International System of Units (SI) and is the standard unit of angular measure used in many areas of mathematics. The unit was formerly an SI supplementary unit (before that ...

(rad) is equal to one (). * The

steradian The steradian (symbol: sr) or square radian is the unit of solid angle in the International System of Units (SI). It is used in three-dimensional geometry, and is analogous to the radian, which quantifies planar angles. Whereas an angle in radian ...

(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 The joule ( , ; symbol: J) is the unit of energy in the International System of Units (SI). It is equal to the amount of work done when a force of 1 newton displaces a mass through a distance of 1 metre in the direction of the force appli ...

(J) is equal to one newton-metre (). * The

watt The watt (symbol: W) is the unit of power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantify the rate of energy transfer. The watt is named after James ...

(W) is equal to one joule per second (). * The

coulomb The coulomb (symbol: C) is the unit of electric charge in the International System of Units (SI). In the present version of the SI it is equal to the electric charge delivered by a 1 ampere constant current in 1 second and to elementary char ...

volt The volt (symbol: V) is the unit of electric potential, electric potential difference (voltage), and electromotive force in the International System of Units (SI). It is named after the Italian physicist Alessandro Volta (1745–1827). Defin ...

(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 The farad (symbol: F) is the unit of electrical capacitance, the ability of a body to store an electrical charge, in the International System of Units (SI). It is named after the English physicist Michael Faraday (1791–1867). In SI base unit ...

(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 Siemens AG ( ) is a German multinational conglomerate corporation and the largest industrial manufacturing company in Europe headquartered in Munich with branch offices abroad. The principal divisions of the corporation are ''Industry'', ''E ...

(S) is equal to one ampere per volt (). * The henry (H) is equal to one volt-second per ampere (). * The degree Celsius (°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

(). * 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 compose ...

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

sievert The sievert (symbol: SvNot be confused with the sverdrup or the svedberg, two non-SI units that sometimes use the same symbol.) is a unit in the International System of Units (SI) intended to represent the stochastic health risk of ionizing rad ...

(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 prefix A metric prefix is a unit prefix that precedes a basic unit of measure to indicate a multiple or submultiple of the unit. All metric prefixes used today are decadic. Each prefix has a unique symbol that is prepended to any unit symbol. The pr ...

es 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 ...

(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 The vacuum magnetic permeability (variously ''vacuum permeability'', ''permeability of free space'', ''permeability of vacuum''), also known as the magnetic constant, is the magnetic permeability in a classical vacuum. It is a physical constan ...

''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 In the physical sciences, the wavenumber (also wave number or repetency) is the '' spatial frequency'' of a wave, measured in cycles per unit distance (ordinary wavenumber) or radians per unit distance (angular wavenumber). It is analogous to te ...

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 ...

equal to . * The

dyne The dyne (symbol: dyn; ) is a derived unit of force specified in the centimetre–gram–second (CGS) system of units, a predecessor of the modern SI. History The name dyne was first proposed as a CGS unit of force in 1873 by a Committee of ...

(dyn) is a unit of

force In physics, a force is an influence that can change the motion of an object. A force can cause an object with mass to change its velocity (e.g. moving from a state of rest), i.e., to accelerate. Force can also be described intuitively as a ...

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 Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country a ...

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 In physics, energy (from Ancient Greek: ἐνέργεια, ''enérgeia'', “activity”) is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of ...

equal to (). * The poise (P) is a unit of

dynamic viscosity The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water. Viscosity quantifies the int ...

equal to (). * The stokes (St) is a unit of kinematic viscosity equal to (). * The stilb (sb) is a unit of

luminance Luminance is a photometric measure of the luminous intensity per unit area of light travelling in a given direction. It describes the amount of light that passes through, is emitted from, or is reflected from a particular area, and falls with ...

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 a ...

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. Tha ...

(statC) or franklin (Fr) is a unit of

electric charge Electric charge is the physical property of matter that causes charged matter to experience a force when placed in an electromagnetic field. Electric charge can be ''positive'' or ''negative'' (commonly carried by protons and electrons res ...

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

equal to , corresponding to ~. * The statvolt (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 Kennelly ...

(abC) is a unit of

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 The British Indian Ocean Territory (BIOT) is an Overseas Territory of the United Kingdom situated in the Indian Ocean, halfway between Tanzania and Indonesia. The territory comprises the seven atolls of the Chagos Archipelago with over 1, ...

(Bi) is a unit of

, corresponding to . * The abvolt (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 nanoohm. ...

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

, corresponding to . * The

abhenry The abhenry is the CGS (centimetre–gram–second) electromagnetic In physics, electromagnetism is an interaction that occurs between particles with electric charge. It is the second-strongest of the four fundamental interactions, after ...

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 The oersted (symbol Oe) is the coherent derived unit of the auxiliary magnetic field H in the centimetre–gram–second system of units (CGS). It is equivalent to 1 dyne per maxwell. Difference between CGS and SI systems In the CGS system, ...

(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 franklin (Fr) is a unit of

equal to , corresponding to ~. * The

(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 The tonne ( or ; symbol: t) is a unit of mass equal to 1000 kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton to distinguish it from the non-metric units of the short ton ( United State ...

(t) is a unit of

equal to . * The sthène (sn) is a unit of

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

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 Frequency is the number of occurrences of a repeating event per unit of time. It is also occasionally referred to as ''temporal frequency'' for clarity, and is distinct from ''angular frequency''. Frequency is measured in hertz (Hz) which is eq ...

equal to . * The MKS

is a unit of acoustic impedance 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- ...

(kgf), also kilopond (kp), is a unit of

(). * The hyl is a unit of

equal to (). * The poncelet (p) is a unit of

equal to (). * The

technical atmosphere Technical may refer to: * Technical (vehicle), an improvised fighting vehicle * Technical analysis, a discipline for forecasting the future direction of prices through the study of past market data * Technical drawing, showing how something is co ...

(at) is a (non-coherent) unit of

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 Nuclear physics is the field of physics that studies atomic nuclei and their constituents and interactions, in addition to the study of other forms of nuclear matter. Nuclear physics should not be confused with atomic physics, which studies t ...

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 Chemistry is the scientific study of the properties and behavior of matter. It is a natural science that covers the elements that make up matter to the compounds made of atoms, molecules and ions: their composition, structure, proper ...

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 wit ...

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 micrometre (American and British English spelling differences#-re, -er, international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American and British English spelling differences# ...

(). * The basic module (M) is a unit of distance equal to one hundred millimetres (). * The myriametre (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 A shed is typically a simple, single-story roofed structure that is used for hobbies, or as a workshop in a back garden or on an allotment. Sheds vary considerably in their size and complexity of construction, from simple open-sided ones desi ...

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.Alle ...

s (100 rm² = 10⁻⁵² m²). * The

outhouse An outhouse is a small structure, separate from a main building, which covers a toilet. This is typically either a pit latrine or a bucket toilet, but other forms of dry (non-flushing) toilets may be encountered. The term may also be use ...

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 The hectare (; SI symbol: ha) is a non-SI metric unit of area equal to a square with 100- metre sides (1 hm2), or 10,000 m2, and is primarily used in the measurement of land. There are 100 hectares in one square kilometre. An acre i ...

(ha) is a unit of area equal to .

Volume

* The

lambda Lambda (}, ''lám(b)da'') is the 11th letter of the Greek alphabet, representing the voiced alveolar lateral approximant . In the system of Greek numerals, lambda has a value of 30. Lambda is derived from the Phoenician Lamed . Lambda gave ri ...

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

millimetre 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 English spelling differences#-re, -er, ...

(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 (1 dm³). * The

stere The stere or stère (st) is a unit of volume in the original metric system equal to one cubic metre. The stere is typically used for measuring large quantities of firewood or other cut wood, while the cubic meter is used for uncut wood. The na ...

(st) is a unit of volume equal to .

Reciprocal length

* The

dioptre A dioptre (British spelling) or diopter (American spelling) is a unit of measurement with dimension of reciprocal length, equivalent to one reciprocal metre, 1 dioptre = 1 m−1. It is normally used to express the optical power of a lens or ...

is a unit of

optical power In optics, optical power (also referred to as dioptric power, refractive power, focusing power, or convergence power) is the degree to which a lens, mirror, or other optical system converges or diverges light. It is equal to the reciprocal of the ...

equal to one reciprocal metre ().

Time

* The svedberg (S or Sv) is a unit of time used in chemistry equal to one hundred

femtosecond A femtosecond is a unit of time in the International System of Units (SI) equal to 10 or of a second; that is, one quadrillionth, or one millionth of one billionth, of a second. For context, a femtosecond is to a second as a second is to about 31 ...

s (). * The shake is a unit of time used in nuclear physics equal to ten

nanosecond A nanosecond (ns) is a unit of time in the International System of Units (SI) equal to one billionth of a second, that is, of a second, or 10 seconds. The term combines the SI prefix ''nano-'' indicating a 1 billionth submultiple of an SI unit ( ...

s (). * The

sigma Sigma (; uppercase Σ, lowercase σ, lowercase in word-final position ς; grc-gre, σίγμα) is the eighteenth letter of the Greek alphabet. In the system of Greek numerals, it has a value of 200. In general mathematics, uppercase Σ is used a ...

is a unit of time equal to one

microsecond A microsecond is a unit of time in the International System of Units (SI) equal to one millionth (0.000001 or 10−6 or ) of a second. Its symbol is μs, sometimes simplified to us when Unicode is not available. A microsecond is equal to 1000 ...

(). * The jiffy is sometimes used to mean a unit of time of .

Reciprocal time

* The fresnel is a unit of

equal to .

Reciprocal time squared

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

Speed

* The benz is a unit of

speed In everyday use and in kinematics, the speed (commonly referred to as ''v'') of an object is the magnitude of the change of its position over time or the magnitude of the change of its position per unit of time; it is thus a scalar quant ...

equal to one metre per second (1 m/s).

Acceleration

* The leo is a unit of acceleration equal to .

Flow rate

* The

sverdrup In oceanography, the sverdrup (symbol: Sv) is a non- SI metric unit of volumetric flow rate, with equal to . It is equivalent to the SI derived unit cubic hectometer per second (symbol: hm3/s or hm3⋅s−1): 1 Sv is equal to 1 hm3/s. It is u ...

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

* The undecimogramme is a unit of

equal to ten picograms (10 pg). * The

gamma Gamma (uppercase , lowercase ; ''gámma'') is the third letter of the Greek alphabet. In the system of Greek numerals it has a value of 3. In Ancient Greek, the letter gamma represented a voiced velar stop . In Modern Greek, this letter r ...

(γ) is a unit of

equal to one microgram (1 μg). * The gravet is a unit of

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 grav ...

is a unit of

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

equal to one megagram (1 Mg).

Linear mass density

* The tex (tex) is a unit of linear mass density 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

defined as 0.1

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

equal to .

Energy

* The foe is a unit of

equal to ().

Viscosity

* The poiseuille is a unit of

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 The debye (symbol: D) (; ) is a CGS unit (a non- SI metric unit) of electric dipole momentTwo equal and opposite charges separated by some distance constitute an electric dipole. This dipole possesses an electric dipole moment whose value is g ...

(D) is a unit of

electric dipole moment The electric dipole moment is a measure of the separation of positive and negative electrical charges within a system, that is, a measure of the system's overall polarity. The SI unit for electric dipole moment is the coulomb- meter (C⋅m). ...

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 United Kingdom Census 2011, 2011 Census. The town lies approximately west of ...

(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

equal to one

per metre squared (). * The lambert (L) is a unit of

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 (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 Albert Einstein ( ; ; 14 March 1879 – 18 April 1955) was a German-born Theoretical physics, theoretical physicist, widely acknowledged to be one of the greatest and most influential physicists of all time. Einstein is best known for d ...

(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 ...

photon A photon () is an elementary particle that is a quantum of the electromagnetic field, including electromagnetic radiation such as light and radio waves, and the force carrier for the electromagnetic force. Photons are massless, so they alwa ...

s, equal to one mole (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 har ...

equal to . * The

roentgen equivalent man The roentgen equivalent man (rem) is a CGS unit of equivalent dose, effective dose, and committed dose, which are dose measures used to estimate potential health effects of low levels of ionizing radiation on the human body. Quantities measu ...

(rem) is a unit of

equivalent dose Equivalent dose is a dose quantity '' H '' representing the stochastic health effects of low levels of ionizing radiation on the human body which represents the probability of radiation-induced cancer and genetic damage. It is derived from the p ...

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 ...

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 micromole of substrate per min ...

(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 (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 A millimetre of mercury is a manometric unit of pressure, formerly defined as the extra pressure generated by a column of mercury one millimetre high, and currently defined as exactly pascals. It is denoted mmHg or mm Hg. Although not an ...

(mmHg) is approximately . * The

torr The torr (symbol: Torr) is a unit of pressure based on an absolute scale, defined as exactly of a standard atmosphere (). Thus one torr is exactly (≈ ). Historically, one torr was intended to be the same as one " millimeter of merc ...

(Torr) is approximately 133.3224 pascals. * The centimetre of mercury (cmHg) is approximately . * The

electronvolt In physics, an electronvolt (symbol eV, also written electron-volt and electron volt) is the measure of an amount of kinetic energy gained by a single electron accelerating from rest through an electric potential difference of one volt in vacu ...

(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 o ...

(cal) is . * The langley (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 Measuring tape with inches The inch (symbol: in or ″) is a unit of length in the British imperial and the United States customary systems of measurement. It is equal to yard or of a foot. Derived from the Roman uncia ("twelfth ...

, 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 The neper (symbol: Np) is a logarithmic unit for ratios of measurements of physical field and power quantities, such as gain and loss of electronic signals. The unit's name is derived from the name of John Napier, the inventor of logarithms. A ...

(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 (mathematics), fraction of 100. It is often Denotation, denoted using the percent sign, "%", although the abbreviations "pct.", "p ...

(%) 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 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, t ...

(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 (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 (''mil'') is equal to ten kilometres (). * The metric dunam is equal to one thousand metres squared (). * The stremma 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 Dan or DAN may refer to: People * Dan (name), including a list of people with the name ** Dan (king), several kings of Denmark * Dan people, an ethnic group located in West Africa **Dan language, a Mande language spoken primarily in Côte d'Ivoir ...

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 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 A metric mile is a colloquial term used in some countries for the 1500 meters, the premier middle distance running event in international track and field. The term 'metric mile' (0.93 statute miles) was applied to this distance because it appr ...

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