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International System of Units (SI)

The modern form of the metric system, which has been adopted by the United States and most other nations.
Note: The SI is constructed from seven base units for independent physical quantities. Tables showing these values are included below and are current as of Fall
199
5. SI Prefixes. The common metric prefixes are: Multiplication FactorPrefix NamePrefix Symbol1 000 000 000 000 000 000 000 000 =1024 yottaY1 000 000 000 000 000 000 000 =1021 zettaZ1 000 000 000 000 000 000 =1018 exaE1 000 000 000 000 000 =1015 petaP1 000 000 000 000 =1012 teraT1 000 000 000 =109 gigaG1 000 000 =106 megaM1 000 =103 kilok100 =102 hectoh10 =101 dekada0.1 =10-1 decid0.01 =10-2 centic0.001 =10-3 millim0.000 001 =10-6 micro
0. 000 000 001 =10-9 nanon0.000 000 000 001 =10-12 picop0.000 000 000 000 001 =10-15 femtof0.000 000 000 000 000 001 =10-18 attoa0.000 000 000 000 000 000 001 =10-21 zeptoz0.000 000 000 000 000 000 000 001 =10-24 yoctoySI Base Units:Quantity Unit Name Unit Symbol lengthmetermmasskilogramkgtime secondselectric currentampereAthermodynamic temperature kelvin Kamount of substancemolemolluminous intensity candela cdSI derived units. Derived units are formed by combining base units and other derived units according to the algebraic relations linking the corresponding quantities. The symbols for derived units are obtained by means of the mathematical signs for multiplication, division, and use of exponents. For example, the SI unit for velocity is the meter per second (m/s or m•s-1), and that for angular velocity is the radian per second (rad/s or rad•s-1). Some derived SI units have been given special names and symbols, as listed in this table:QuantityUnit NameUnit SymbolExpression in Terms of Other SI UnitsAbsorbed dose, specific energy imparted, kerma, absorbed dose indexgrayGyJ/kgActivity (of a radionuclide)becquerelBq1/sCelsius temperaturedegree CelsiusCKDose equivalentsievertSvJ/kgElectric capacitancefaradFC/VElectric charge, quantity of electricitycoulombCA•sElectric conductancesiemensSA/VElectric inductance henryHWb/AElectric potential, potential difference, electromotive forcevoltVW/AElectric resistanceohm V/AEnergy, work, quantity of heatjouleJN•mForcenewtonNkg•m/s2 Frequency (of a periodic phenomenon)hertz Hz1/sIlluminanceluxlxlm/m2 Luminous flux lumenlmcd•srMagnetic flux weberWbV•sMagnetic flux density teslaTWb/m2 Plane angleradian rad m/mPower, radiant flux wattWJ/sPressure, stresspascalPaN/m2 Solid anglesteradian srm2/m2