Constants (scipy.constants)

Physical and mathematical constants and units.

Mathematical constants

pi Pi
golden Golden ratio

Physical constants

c speed of light in vacuum
mu_0 the magnetic constant \mu_0
epsilon_0 the electric constant (vacuum permittivity), \epsilon_0
h the Planck constant h
hbar \hbar = h/(2\pi)
G Newtonian constant of gravitation
g standard acceleration of gravity
e elementary charge
R molar gas constant
alpha fine-structure constant
N_A Avogadro constant
k Boltzmann constant
sigma Stefan-Boltzmann constant \sigma
Wien Wien displacement law constant
Rydberg Rydberg constant
m_e electron mass
m_p proton mass
m_n neutron mass

Constants database

In addition to the above variables containing physical constants, scipy.constants also contains a database of additional physical constants.

value(key) Value in physical_constants indexed by key
unit(key) Unit in physical_constants indexed by key
precision(key) Relative precision in physical_constants indexed by key
find(sub) Return list of codata.physical_constant keys containing a given string
scipy.constants.physical_constants

Dictionary of physical constants, of the format physical_constants[name] = (value, unit, uncertainty).

Available constants:

alpha particle mass  
alpha particle mass energy equivalent  
alpha particle mass energy equivalent in MeV  
alpha particle mass in u  
alpha particle molar mass  
alpha particle-electron mass ratio  
alpha particle-proton mass ratio  
Angstrom star  
atomic mass constant  
atomic mass constant energy equivalent  
atomic mass constant energy equivalent in MeV  
atomic mass unit-electron volt relationship  
atomic mass unit-hartree relationship  
atomic mass unit-hertz relationship  
atomic mass unit-inverse meter relationship  
atomic mass unit-joule relationship  
atomic mass unit-kelvin relationship  
atomic mass unit-kilogram relationship  
atomic unit of 1st hyperpolarizablity  
atomic unit of 2nd hyperpolarizablity  
atomic unit of action  
atomic unit of charge  
atomic unit of charge density  
atomic unit of current  
atomic unit of electric dipole moment  
atomic unit of electric field  
atomic unit of electric field gradient  
atomic unit of electric polarizablity  
atomic unit of electric potential  
atomic unit of electric quadrupole moment  
atomic unit of energy  
atomic unit of force  
atomic unit of length  
atomic unit of magnetic dipole moment  
atomic unit of magnetic flux density  
atomic unit of magnetizability  
atomic unit of mass  
atomic unit of momentum  
atomic unit of permittivity  
atomic unit of time  
atomic unit of velocity  
Avogadro constant  
Bohr magneton  
Bohr magneton in eV/T  
Bohr magneton in Hz/T  
Bohr magneton in inverse meters per tesla  
Bohr magneton in K/T  
Bohr radius  
Boltzmann constant  
Boltzmann constant in eV/K  
Boltzmann constant in Hz/K  
Boltzmann constant in inverse meters per kelvin  
characteristic impedance of vacuum  
classical electron radius  
Compton wavelength  
Compton wavelength over 2 pi  
conductance quantum  
conventional value of Josephson constant  
conventional value of von Klitzing constant  
Cu x unit  
deuteron magnetic moment  
deuteron magnetic moment to Bohr magneton ratio  
deuteron magnetic moment to nuclear magneton ratio  
deuteron mass  
deuteron mass energy equivalent  
deuteron mass energy equivalent in MeV  
deuteron mass in u  
deuteron molar mass  
deuteron rms charge radius  
deuteron-electron magnetic moment ratio  
deuteron-electron mass ratio  
deuteron-neutron magnetic moment ratio  
deuteron-proton magnetic moment ratio  
deuteron-proton mass ratio  
electric constant  
electron charge to mass quotient  
electron g factor  
electron gyromagnetic ratio  
electron gyromagnetic ratio over 2 pi  
electron magnetic moment  
electron magnetic moment anomaly  
electron magnetic moment to Bohr magneton ratio  
electron magnetic moment to nuclear magneton ratio  
electron mass  
electron mass energy equivalent  
electron mass energy equivalent in MeV  
electron mass in u  
electron molar mass  
electron to alpha particle mass ratio  
electron to shielded helion magnetic moment ratio  
electron to shielded proton magnetic moment ratio  
electron volt  
electron volt-atomic mass unit relationship  
electron volt-hartree relationship  
electron volt-hertz relationship  
electron volt-inverse meter relationship  
electron volt-joule relationship  
electron volt-kelvin relationship  
electron volt-kilogram relationship  
electron-deuteron magnetic moment ratio  
electron-deuteron mass ratio  
electron-muon magnetic moment ratio  
electron-muon mass ratio  
electron-neutron magnetic moment ratio  
electron-neutron mass ratio  
electron-proton magnetic moment ratio  
electron-proton mass ratio  
electron-tau mass ratio  
elementary charge  
elementary charge over h  
Faraday constant  
Faraday constant for conventional electric current  
Fermi coupling constant  
fine-structure constant  
first radiation constant  
first radiation constant for spectral radiance  
Hartree energy  
Hartree energy in eV  
hartree-atomic mass unit relationship  
hartree-electron volt relationship  
hartree-hertz relationship  
hartree-inverse meter relationship  
hartree-joule relationship  
hartree-kelvin relationship  
hartree-kilogram relationship  
helion mass  
helion mass energy equivalent  
helion mass energy equivalent in MeV  
helion mass in u  
helion molar mass  
helion-electron mass ratio  
helion-proton mass ratio  
hertz-atomic mass unit relationship  
hertz-electron volt relationship  
hertz-hartree relationship  
hertz-inverse meter relationship  
hertz-joule relationship  
hertz-kelvin relationship  
hertz-kilogram relationship  
inverse fine-structure constant  
inverse meter-atomic mass unit relationship  
inverse meter-electron volt relationship  
inverse meter-hartree relationship  
inverse meter-hertz relationship  
inverse meter-joule relationship  
inverse meter-kelvin relationship  
inverse meter-kilogram relationship  
inverse of conductance quantum  
Josephson constant  
joule-atomic mass unit relationship  
joule-electron volt relationship  
joule-hartree relationship  
joule-hertz relationship  
joule-inverse meter relationship  
joule-kelvin relationship  
joule-kilogram relationship  
kelvin-atomic mass unit relationship  
kelvin-electron volt relationship  
kelvin-hartree relationship  
kelvin-hertz relationship  
kelvin-inverse meter relationship  
kelvin-joule relationship  
kelvin-kilogram relationship  
kilogram-atomic mass unit relationship  
kilogram-electron volt relationship  
kilogram-hartree relationship  
kilogram-hertz relationship  
kilogram-inverse meter relationship  
kilogram-joule relationship  
kilogram-kelvin relationship  
lattice parameter of silicon  
Loschmidt constant (273.15 K, 101.325 kPa)  
magnetic constant  
magnetic flux quantum  
Mo x unit  
molar gas constant  
molar mass constant  
molar mass of carbon-12  
molar Planck constant  
molar Planck constant times c  
molar volume of ideal gas (273.15 K, 100 kPa)  
molar volume of ideal gas (273.15 K, 101.325 kPa)  
molar volume of silicon  
muon Compton wavelength  
muon Compton wavelength over 2 pi  
muon g factor  
muon magnetic moment  
muon magnetic moment anomaly  
muon magnetic moment to Bohr magneton ratio  
muon magnetic moment to nuclear magneton ratio  
muon mass  
muon mass energy equivalent  
muon mass energy equivalent in MeV  
muon mass in u  
muon molar mass  
muon-electron mass ratio  
muon-neutron mass ratio  
muon-proton magnetic moment ratio  
muon-proton mass ratio  
muon-tau mass ratio  
natural unit of action  
natural unit of action in eV s  
natural unit of energy  
natural unit of energy in MeV  
natural unit of length  
natural unit of mass  
natural unit of momentum  
natural unit of momentum in MeV/c  
natural unit of time  
natural unit of velocity  
neutron Compton wavelength  
neutron Compton wavelength over 2 pi  
neutron g factor  
neutron gyromagnetic ratio  
neutron gyromagnetic ratio over 2 pi  
neutron magnetic moment  
neutron magnetic moment to Bohr magneton ratio  
neutron magnetic moment to nuclear magneton ratio  
neutron mass  
neutron mass energy equivalent  
neutron mass energy equivalent in MeV  
neutron mass in u  
neutron molar mass  
neutron to shielded proton magnetic moment ratio  
neutron-electron magnetic moment ratio  
neutron-electron mass ratio  
neutron-muon mass ratio  
neutron-proton magnetic moment ratio  
neutron-proton mass ratio  
neutron-tau mass ratio  
Newtonian constant of gravitation  
Newtonian constant of gravitation over h-bar c  
nuclear magneton  
nuclear magneton in eV/T  
nuclear magneton in inverse meters per tesla  
nuclear magneton in K/T  
nuclear magneton in MHz/T  
Planck constant  
Planck constant in eV s  
Planck constant over 2 pi  
Planck constant over 2 pi in eV s  
Planck constant over 2 pi times c in MeV fm  
Planck length  
Planck mass  
Planck temperature  
Planck time  
proton charge to mass quotient  
proton Compton wavelength  
proton Compton wavelength over 2 pi  
proton g factor  
proton gyromagnetic ratio  
proton gyromagnetic ratio over 2 pi  
proton magnetic moment  
proton magnetic moment to Bohr magneton ratio  
proton magnetic moment to nuclear magneton ratio  
proton magnetic shielding correction  
proton mass  
proton mass energy equivalent  
proton mass energy equivalent in MeV  
proton mass in u  
proton molar mass  
proton rms charge radius  
proton-electron mass ratio  
proton-muon mass ratio  
proton-neutron magnetic moment ratio  
proton-neutron mass ratio  
proton-tau mass ratio  
quantum of circulation  
quantum of circulation times 2  
Rydberg constant  
Rydberg constant times c in Hz  
Rydberg constant times hc in eV  
Rydberg constant times hc in J  
Sackur-Tetrode constant (1 K, 100 kPa)  
Sackur-Tetrode constant (1 K, 101.325 kPa)  
second radiation constant  
shielded helion gyromagnetic ratio  
shielded helion gyromagnetic ratio over 2 pi  
shielded helion magnetic moment  
shielded helion magnetic moment to Bohr magneton ratio  
shielded helion magnetic moment to nuclear magneton ratio  
shielded helion to proton magnetic moment ratio  
shielded helion to shielded proton magnetic moment ratio  
shielded proton gyromagnetic ratio  
shielded proton gyromagnetic ratio over 2 pi  
shielded proton magnetic moment  
shielded proton magnetic moment to Bohr magneton ratio  
shielded proton magnetic moment to nuclear magneton ratio  
speed of light in vacuum  
standard acceleration of gravity  
standard atmosphere  
Stefan-Boltzmann constant  
tau Compton wavelength  
tau Compton wavelength over 2 pi  
tau mass  
tau mass energy equivalent  
tau mass energy equivalent in MeV  
tau mass in u  
tau molar mass  
tau-electron mass ratio  
tau-muon mass ratio  
tau-neutron mass ratio  
tau-proton mass ratio  
Thomson cross section  
unified atomic mass unit  
von Klitzing constant  
weak mixing angle  
Wien displacement law constant  
{220} lattice spacing of silicon  

Unit prefixes

SI

yotta 10^{24}
zetta 10^{21}
exa 10^{18}
peta 10^{15}
tera 10^{12}
giga 10^{9}
mega 10^{6}
kilo 10^{3}
hecto 10^{2}
deka 10^{1}
deci 10^{-1}
centi 10^{-2}
milli 10^{-3}
micro 10^{-6}
nano 10^{-9}
pico 10^{-12}
femto 10^{-15}
atto 10^{-18}
zepto 10^{-21}

Binary

kibi 2^{10}
mebi 2^{20}
gibi 2^{30}
tebi 2^{40}
pebi 2^{50}
exbi 2^{60}
zebi 2^{70}
yobi 2^{80}

Units

Weight

gram 10^{-3} kg
metric_ton 10^{3} kg
grain one grain in kg
lb one pound (avoirdupous) in kg
oz one ounce in kg
stone one stone in kg
grain one grain in kg
long_ton one long ton in kg
short_ton one short ton in kg
troy_ounce one Troy ounce in kg
troy_pound one Troy pound in kg
carat one carat in kg
m_u atomic mass constant (in kg)

Angle

degree degree in radians
arcmin arc minute in radians
arcsec arc second in radians

Time

minute one minute in seconds
hour one hour in seconds
day one day in seconds
week one week in seconds
year one year (365 days) in seconds
Julian_year one Julian year (365.25 days) in seconds

Length

inch one inch in meters
foot one foot in meters
yard one yard in meters
mile one mile in meters
mil one mil in meters
pt one point in meters
survey_foot one survey foot in meters
survey_mile one survey mile in meters
nautical_mile one nautical mile in meters
fermi one Fermi in meters
angstrom one Ångström in meters
micron one micron in meters
au one astronomical unit in meters
light_year one light year in meters
parsec one parsec in meters

Pressure

atm standard atmosphere in pascals
bar one bar in pascals
torr one torr (mmHg) in pascals
psi one psi in pascals

Area

hectare one hectare in square meters
acre one acre in square meters

Volume

liter one liter in cubic meters
gallon one gallon (US) in cubic meters
gallon_imp one gallon (UK) in cubic meters
fluid_ounce one fluid ounce (US) in cubic meters
fluid_ounce_imp one fluid ounce (UK) in cubic meters
bbl one barrel in cubic meters

Speed

kmh kilometers per hour in meters per second
mph miles per hour in meters per second
mach one Mach (approx., at 15 °C, 1 atm) in meters per second
knot one knot in meters per second

Temperature

zero_Celsius zero of Celsius scale in Kelvin
degree_Fahrenheit one Fahrenheit (only differences) in Kelvins
C2K(C) Convert Celsius to Kelvin
K2C(K) Convert Kelvin to Celsius
F2C(F) Convert Fahrenheit to Celsius
C2F(C) Convert Celsius to Fahrenheit
F2K(F) Convert Fahrenheit to Kelvin
K2F(K) Convert Kelvin to Fahrenheit

Energy

eV one electron volt in Joules
calorie one calorie (thermochemical) in Joules
calorie_IT one calorie (International Steam Table calorie, 1956) in Joules
erg one erg in Joules
Btu one British thermal unit (International Steam Table) in Joules
Btu_th one British thermal unit (thermochemical) in Joules
ton_TNT one ton of TNT in Joules

Power

hp one horsepower in watts

Force

dyn one dyne in watts
lbf one pound force in watts
kgf one kilogram force in watts

Optics

lambda2nu(lambda_) Convert wavelength to optical frequency
nu2lambda(nu) Convert optical frequency to wavelength.