Metric system

In mathematics, we find physical quantities such as length, mass, temperature, among others. These quantities are associated with certain quantities and a measurement standard called a unit of measurement or simply a unit. A magnitude is any physical property that can be expressed numerically.

A unit is a standardized quantity of a certain physical quantity. By standardized we mean that it takes its value from a pattern. Each physical quantity has a predefined (or basic) unit of measurement.

The metric system or International System of Units (SI) is the system most used at the measurement level. It consists of a set of seven fundamental (or basic) units, which express seven physical quantities; from these other units (known as derivatives) are determined.

Fundamental Units

Fundamental quantitiesFundamental unitSymbol
Lengthmeterm
Doughkilogramkg
Timeseconds
Electric current intensityamp or ampereA
TemperatureKelvinK
Amount of substancemolemole
Luminous intensitycandlecd

Derived units

Derived quantitiesFundamental unitSymbol
Surfacesquare meterm2
Volumecubic meterm3
Speedmeter per secondm / s
Accelerationmeter per second squaredm / s2
Mass by volumekilogram per cubic meterkg / m3
Angular velocityradian per secondrad / s
Angular accelerationradian per second squaredrad / s2
FrequencyhertzHz
ForceNewtonN
PressurepascalPa
Energy, work,
amount of heat
jouleJ
PowerwattW
Amount of electricity
electric charge
coulombC
Electric potential
electromotive force
voltV
Electric resistanceohmW
Electrical capacityfaradF
Magnetic fluxweberWb
Magnetic inductionteslaT
InductanceHenryH

Supplementary Units

Fundamental quantitiesFundamental unitSymbol
Plane angleradianrad
Solid anglesteradiansr

SI prefixes

Unit symbols can be affected by prefixes that act as decimal multiples and submultiples. These prefixes are placed in front of the corresponding unit symbol with no space between.

Decimal multiplesDecimal Submultiples
PrefixSymbolFactorPrefixSymbolFactor
decada101decid10-1
hectoh102centic10-2
kilok103millim10-3
megaM106microμ10-6
jigG109nanon10-9
teraT1012picop10-12
petaP1015femtoF10-15
exaE1018attoa10-18
zettaZ1021zeptoz10-21
yottaY1024yoctoy10-24