What is the International System of Units?

The International System of Units, sometimes abbreviated as SI, is the measurement system officially adopted almost everywhere in the world. It consists of a set of seven base units that include second, meter, kilogram, ampere, kelvin, mole, and candela. These units allow an unlimited number of additional derived units, through which it is theoretically possible to measure everything in the universe.

Units of measure that derive from base units

This list presents a set of 22 derivative units that have been assigned a name and respective symbol, which can be obtained by combining the base units.

Quantity
Name
Unit
Symbol
Unit
Name
In SI
Base Units
Absorbed Dose (of Ionising Radiation)GyGraym2⋅s−2
CapacitanceFFaradkg−1⋅m−2⋅s4⋅A2
Catalytic ActivitykatKatalmol⋅s−1
Electric ChargeCCoulombs⋅A
Electrical ConductanceSSiemenskg−1⋅m−2⋅s3⋅A2
Electrical Potential Difference (Voltage), emfVVoltkg⋅m2⋅s−3⋅A−1
Energy, Work, HeatJJoulekg⋅m2⋅s−2
Equivalent Dose (of Ionising Radiation)SvSievertm2⋅s−2
Force, WeightNNewtonkg⋅m⋅s−2
FrequencyHzHertzs−1
IlluminancelxLuxm−2⋅cd
InductanceHHenrykg⋅m2⋅s−2⋅A−2
Luminous FluxlmLumencd⋅sr
Magnetic FluxWbWeberkg⋅m2⋅s−2⋅A−1
Magnetic Flux DensityTTeslakg⋅s−2⋅A−1
Plane AngleradRadianm/m
Power, Radiant FluxWWattkg⋅m2⋅s−3
Pressure, StressPaPascalkg⋅m−1⋅s−2
Radioactivity (Decays per Unit Time)BqBecquerels−1
Resistance, Impedance, ReactanceΩOhmkg⋅m2⋅s−3⋅A−2
Solid AnglesrSteradianm2/m2
Temperature Relative to 273.15 K°CDegree CelsiusK