SI Units: https://en.wikipedia.org/wiki/International_System_of_Units SI base units --------------- Name | Symbol | Dimension | Quantity -------------------------------------------- second | s | T | time metre | m | L | length kilogram | kg | M | mass ampere | A | I | electric current kelvin | K | Θ | thermodynamic temperature mole | mol | N | amount of substance candela | cd | J | luminous intensity SI prefixes -------------- Prefix | Base 10 | Decimal | English word | Adoption[nb 1] Name | Symbol | | | Short scale | Long scale | ----------------------------------------------------------------------------------------------------- yotta | Y | 10^24 | 1000000000000000000000000 | septillion | quadrillion | 1991 zetta | Z | 10^21 | 1000000000000000000000 | sextillion | trilliard | 1991 exa | E | 10^18 | 1000000000000000000 | quintillion | trillion | 1975 peta | P | 10^15 | 1000000000000000 | quadrillion | billiard | 1975 tera | T | 10^12 | 1000000000000 | trillion | billion | 1960 giga | G | 10^9 | 1000000000 | billion | milliard | 1960 mega | M | 10^6 | 1000000 | million | 1873 kilo | k | 10^3 | 1000 | thousand | 1795 hecto | h | 10^2 | 100 | hundred | 1795 deca | da | 10^1 | 10 | ten | 1795 | | 10^0 | 1 | one | – deci | d | 10^−1 | 0.1 | tenth | 1795 centi | c | 10^−2 | 0.01 | hundredth | 1795 milli | m | 10^−3 | 0.001 | thousandth | 1795 micro | μ | 10^−6 | 0.000001 | millionth | 1873 nano | n | 10^−9 | 0.000000001 | billionth | milliardth | 1960 pico | p | 10^−12 | 0.000000000001 | trillionth | billionth | 1960 femto | f | 10^−15 | 0.000000000000001 | quadrillionth | billiardth | 1964 atto | a | 10^−18 | 0.000000000000000001 | quintillionth | trillionth | 1964 zepto | z | 10^−21 | 0.000000000000000000001 | sextillionth | trilliardth | 1991 yocto | y | 10^−24 | 0.000000000000000000000001 | septillionth | quadrillionth | 1991 Derived SI units ---------------- Name | Symbol | Quantity | In SI base units | Equivalents | In other SI units --------------------------------------------------------------------------------------------------------------------------------------- radian[N 1] | rad | plane angle | m/m | m/m | 1 steradian[N 1] | sr | solid angle | m2/m2 | m2/m2 | 1 hertz | Hz | frequency | s−1 | 1/s | newton | N | force, weight | kg⋅m⋅s−2 | kg⋅m/s2 | pascal | Pa | pressure, stress | kg⋅m−1⋅s−2 | N/m2 | N/m2 joule | J | energy, work, heat | kg⋅m2⋅s−2 | m⋅N, C⋅V, W⋅s | N⋅m = Pa⋅m3 watt | W | power, radiant flux | kg⋅m2⋅s−3 | J/s, V⋅A | J/s coulomb | C | electric charge | s⋅A | s⋅A, F⋅V | volt | V | electrical potential difference (voltage), emf | kg⋅m2⋅s−3⋅A−1 | W/A, J/C | W/A = J/C farad | F | capacitance | kg−1⋅m−2⋅s4⋅A2 | C/V, s/Ω | C/V ohm | Ω | resistance, impedance, reactance | kg⋅m2⋅s−3⋅A−2 | 1/S, V/A | V/A siemens | S | electrical conductance | kg−1⋅m−2⋅s3⋅A2 | 1/Ω, A/V | Ω−1 weber | Wb | magnetic flux | kg⋅m2⋅s−2⋅A−1 | J/A, T⋅m2,V⋅s | V⋅s tesla | T | magnetic flux density | kg⋅s−2⋅A−1 | V⋅s/m2, Wb/m2, N/(A⋅m) | Wb/m2 henry | H | inductance | kg⋅m2⋅s−2⋅A−2 | V⋅s/A, Ω⋅s, Wb/A | Wb/A degree Celsius | °C | temperature relative to 273.15 K | K | K | K lumen | lm | luminous flux | cd⋅sr | cd.sr, cd | cd⋅sr lux | lx | illuminance | cd⋅sr⋅m−2 | lm/m2, cd⋅m−2 | cd⋅sr⋅m−2 becquerel | Bq | radioactivity (decays per unit time) | s−1 | 1/s | gray | Gy | absorbed dose (of ionising radiation) | m2⋅s−2 | J/kg | J/kg sievert | Sv | equivalent dose (of ionising radiation) | m2⋅s−2 | J/kg | J/kg katal | kat | catalytic activity | mol⋅s−1 | mol/s | Examples of coherent derived units in terms of base units[36]:17 ----------------------------------------------------------------- Name | Symbol | Derived quantity | Typical symbol ------------------------------------------------------------------------------ square metre | m2 | area | A cubic metre | m3 | volume | V metre per second | m/s | speed, velocity | v metre per second squared | m/s2 | acceleration | a reciprocal metre | m−1 | wavenumber | σ, ṽ | | vergence (optics) | V, 1/f kilogram per cubic metre | kg/m3 | density | ρ kilogram per square metre | kg/m2 | surface density | ρA cubic metre per kilogram | m3/kg | specific volume | v ampere per square metre | A/m2 | current density | j ampere per metre | A/m | magnetic field strength | H mole per cubic metre | mol/m3 | concentration | c kilogram per cubic metre | kg/m3 | mass concentration | ρ, γ candela per square metre | cd/m2 | luminance | Lv Examples of derived units that include units with special names[36]:18 ------------------------------------------------------------------------ Name | Symbol | Quantity | In SI base units -------------------------------------------------------------------------------------------------------------------------------------- pascal-second | Pa⋅s | dynamic viscosity | m−1⋅kg⋅s−1 newton-metre | N⋅m | moment of force | m2⋅kg⋅s−2 newton per metre | N/m | surface tension | kg⋅s−2 radian per second | rad/s | angular velocity, angular frequency | s−1 radian per second squared | rad/s2 | angular acceleration | s−2 watt per square metre | W/m2 | heat flux density, irradiance | kg⋅s−3 joule per kelvin | J/K | entropy, heat capacity | m2⋅kg⋅s−2⋅K−1 joule per kilogram-kelvin | J/(kg⋅K) | specific heat capacity, specific entropy | m2⋅s−2⋅K−1 joule per kilogram | J/kg | specific energy | m2⋅s−2 watt per metre-kelvin | W/(m⋅K) | thermal conductivity | m⋅kg⋅s−3⋅K−1 joule per cubic metre | J/m3 | energy density | m−1⋅kg⋅s−2 volt per metre | V/m | electric field strength | m⋅kg⋅s−3⋅A−1 coulomb per cubic metre | C/m3 | electric charge density | m−3⋅s⋅A coulomb per square metre | C/m2 | surface charge density, electric flux density, electric displacement | m−2⋅s⋅A farad per metre | F/m | permittivity | m−3⋅kg−1⋅s4⋅A2 henry per metre | H/m | permeability | m⋅kg⋅s−2⋅A−2 joule per mole | J/mol | molar energy | m2⋅kg⋅s−2⋅mol−1 joule per mole-kelvin | J/(mol⋅K) | molar entropy, molar heat capacity | m2⋅kg⋅s−2⋅K−1⋅mol−1 coulomb per kilogram | C/kg | exposure (x- and γ-rays) | kg−1⋅s⋅A gray per second | Gy/s | absorbed dose rate | m2⋅s−3 watt per steradian | W/sr | radiant intensity | m2⋅kg⋅s−3 watt per square metre-steradian | W/(m2⋅sr) | radiance | kg⋅s−3 katal per cubic metre | kat/m3 | catalytic activity concentration | m−3⋅s−1⋅mol Units officially accepted for use with the SI[edit] ------------------------------------------------------- Name | Symbol | Quantity | Value in SI units ----------------------------------------------------------------------------------- minute | min | time | 1 min = 60 s hour | h | time | 1 h = 60 min = 3,600 s day | d | time | 1 d = 24 h = 1,440 min = 86,400 s astronomical unit | au | length | 1 au = 149597870700 m degree | ° | plane angle | 1° = (π / 180) rad minute | ′ | plane angle | 1′ = (1 / 60)° = (π / 10,800) rad second | ″ | plane angle | 1″ = (1 / 60)′ = (1 / 3,600)° = (π / 648,000) rad hectare | ha | area | 1 ha = 1 hm2 = 10,000 m2 litre | l | volume | 1 l = 1 dm3 = 1,000 cm3 = 0.001 m3 tonne | t | mass | 1 t = 103 kg dalton | Da | mass | 1 Da = 1.66053906660(50)×10−27 kg[2][3]= 1.660 539 066 60(50) yoctograms electronvolt | eV | energy | 1 eV = 1.602176634×10−19 J = 160.217 663 4 zeptojoules neper | Np | logarithmic ratio quantity | — bel | B | logarithmic ratio quantity | — decibel | dB | logarithmic ratio quantity | — Constants ------------ Constant | Value | Derived unit | Description -------------------------------------------------------------------------------------------------------------- ΔνCs | 9192631770 s−1 | second | transition frequency of the caesium-133 atom in Hz c | 299792458 m⋅s−1 | metre | the speed of light in a vacuum h | 6.62607015×10−34 kg⋅m2⋅s−1 | kilogram | planck constant e | 1.602176634×10−19 A⋅s | ampere | elementary charge k | 1.380649×10−23 kg⋅m2⋅K−1⋅s−2 | kelvin | Boltzmann constant NA | 6.02214076×1023 mol−1 | mole | Avogadro constant Kcd | 683 cd⋅sr⋅s3⋅kg−1⋅m−2 | candela | monochromatic radiation of frequency 540×1012 Hz // Other constants: // // Unit conversion constants - miles, feet etc // // Physical constants: // // Gravity - 9.8 m/s^2 // // // sound intensity - W/m2 => kg⋅m2⋅s−3 / m2 => kg⋅s−3 // sound pressure - Pa => kg⋅m−1⋅s−2 // // Generically: // // L^a.M^b.T^c.I^d.Θ^e.N^f.J^g // // struct GenericQuantityUnits // { // std::string name; // std::string symbol; // std::string desc; // int a,b,c,d,e,f,g; // Where these are the exponents to the SI base units // }; //