Physics Constants Explorer
A comprehensive reference of fundamental physical constants, from universal to cosmological scales. Search, filter, sort, and explore the constants that govern our universe.
Values from CODATA 2018 and Planck 2018 results
Showing 44 of 44 constants
Name | Symbol | Value | Unit | Actions |
|---|---|---|---|---|
Atomic mass unit Atomic | u | 1.66053906660 x 10^-27 | kg | |
Avogadro number Universal | N_A | 6.02214076 x 10^23 | mol^-1 | |
Bohr magneton Electromagnetic | mu_B | 9.2740100783 x 10^-24 | J/T | |
Bohr radius Atomic | a_0 | 5.29177210903 x 10^-11 | m | |
Boltzmann constant Universal | k_B | 1.380649 x 10^-23 | J/K | |
Classical electron radius Atomic | r_e | 2.8179403262 x 10^-15 | m | |
CMB temperature Cosmological | T_CMB | 2.72548 | K | |
Compton wavelength Atomic | lambda_C | 2.42631023867 x 10^-12 | m | |
Conductance quantum Electromagnetic | G_0 | 7.748091729 x 10^-5 | S | |
Cosmological constant Cosmological | Lambda | 1.1056 x 10^-52 | m^-2 | |
Coulomb constant Electromagnetic | k_e | 8.9875517923 x 10^9 | N m^2 C^-2 | |
Deuteron mass Nuclear | m_d | 3.3435837724 x 10^-27 | kg | |
Electron g-factor Atomic | g_e | -2.00231930436256 | dimensionless | |
Electron mass Atomic | m_e | 9.1093837015 x 10^-31 | kg | |
Elementary charge Electromagnetic | e | 1.602176634 x 10^-19 | C | |
Fermi coupling constant Nuclear | G_F/(hbar*c)^3 | 1.1663788 x 10^-5 | GeV^-2 | |
Fine-structure constant Atomic | alpha | 7.2973525693 x 10^-3 | dimensionless | |
Gas constant Universal | R | 8.314462618 | J mol^-1 K^-1 | |
Gravitational constant Universal | G | 6.67430 x 10^-11 | m^3 kg^-1 s^-2 | |
Hartree energy Atomic | E_h | 4.3597447222071 x 10^-18 | J | |
Hubble constant Cosmological | H_0 | 67.4 | km/s/Mpc | |
Josephson constant Electromagnetic | K_J | 4.835978484 x 10^14 | Hz/V | |
Magnetic flux quantum Electromagnetic | Phi_0 | 2.067833848 x 10^-15 | Wb | |
Neutron mass Atomic | m_n | 1.67492749804 x 10^-27 | kg | |
Nuclear magneton Nuclear | mu_N | 5.0507837461 x 10^-27 | J/T | |
Planck constant Universal | h | 6.62607015 x 10^-34 | J s | |
Planck length Cosmological | l_P | 1.616255 x 10^-35 | m | |
Planck mass Cosmological | m_P | 2.176434 x 10^-8 | kg | |
Planck temperature Cosmological | T_P | 1.416784 x 10^32 | K | |
Planck time Cosmological | t_P | 5.391247 x 10^-44 | s | |
Proton magnetic moment Nuclear | mu_p | 1.41060674333 x 10^-26 | J/T | |
Proton mass Atomic | m_p | 1.67262192369 x 10^-27 | kg | |
Proton-electron mass ratio Nuclear | m_p/m_e | 1836.15267343 | dimensionless | |
Reduced Planck constant Universal | hbar | 1.054571817 x 10^-34 | J s | |
Rydberg constant Atomic | R_inf | 1.0973731568160 x 10^7 | m^-1 | |
Speed of light in vacuum Universal | c | 2.99792458 x 10^8 | m/s | |
Stefan-Boltzmann constant Universal | sigma | 5.670374419 x 10^-8 | W m^-2 K^-4 | |
Strong coupling constant Nuclear | alpha_s(M_Z) | 0.1179 | dimensionless | |
Vacuum electric permittivity Electromagnetic | epsilon_0 | 8.8541878128 x 10^-12 | F/m | |
Vacuum magnetic permeability Electromagnetic | mu_0 | 1.25663706212 x 10^-6 | N/A^2 | |
von Klitzing constant Electromagnetic | R_K | 2.581280745 x 10^4 | Ohm | |
W boson mass Nuclear | m_W | 80.377 | GeV/c^2 | |
Wien displacement constant Universal | b | 2.897771955 x 10^-3 | m K | |
Z boson mass Nuclear | m_Z | 91.1876 | GeV/c^2 |
Atomic mass unit
uAtomic1.66053906660 x 10^-27kg
Avogadro number
N_AUniversal6.02214076 x 10^23mol^-1
Bohr magneton
mu_BElectromagnetic9.2740100783 x 10^-24J/T
Bohr radius
a_0Atomic5.29177210903 x 10^-11m
Boltzmann constant
k_BUniversal1.380649 x 10^-23J/K
Classical electron radius
r_eAtomic2.8179403262 x 10^-15m
CMB temperature
T_CMBCosmological2.72548K
Compton wavelength
lambda_CAtomic2.42631023867 x 10^-12m
Conductance quantum
G_0Electromagnetic7.748091729 x 10^-5S
Cosmological constant
LambdaCosmological1.1056 x 10^-52m^-2
Coulomb constant
k_eElectromagnetic8.9875517923 x 10^9N m^2 C^-2
Deuteron mass
m_dNuclear3.3435837724 x 10^-27kg
Electron g-factor
g_eAtomic-2.00231930436256dimensionless
Electron mass
m_eAtomic9.1093837015 x 10^-31kg
Elementary charge
eElectromagnetic1.602176634 x 10^-19C
Fermi coupling constant
G_F/(hbar*c)^3Nuclear1.1663788 x 10^-5GeV^-2
Fine-structure constant
alphaAtomic7.2973525693 x 10^-3dimensionless
Gas constant
RUniversal8.314462618 J mol^-1 K^-1
Gravitational constant
GUniversal6.67430 x 10^-11m^3 kg^-1 s^-2
Hartree energy
E_hAtomic4.3597447222071 x 10^-18J
Hubble constant
H_0Cosmological67.4km/s/Mpc
Josephson constant
K_JElectromagnetic4.835978484 x 10^14Hz/V
Magnetic flux quantum
Phi_0Electromagnetic2.067833848 x 10^-15Wb
Neutron mass
m_nAtomic1.67492749804 x 10^-27kg
Nuclear magneton
mu_NNuclear5.0507837461 x 10^-27J/T
Planck constant
hUniversal6.62607015 x 10^-34J s
Planck length
l_PCosmological1.616255 x 10^-35m
Planck mass
m_PCosmological2.176434 x 10^-8kg
Planck temperature
T_PCosmological1.416784 x 10^32K
Planck time
t_PCosmological5.391247 x 10^-44s
Proton magnetic moment
mu_pNuclear1.41060674333 x 10^-26J/T
Proton mass
m_pAtomic1.67262192369 x 10^-27kg
Proton-electron mass ratio
m_p/m_eNuclear1836.15267343dimensionless
Reduced Planck constant
hbarUniversal1.054571817 x 10^-34J s
Rydberg constant
R_infAtomic1.0973731568160 x 10^7m^-1
Speed of light in vacuum
cUniversal2.99792458 x 10^8m/s
Stefan-Boltzmann constant
sigmaUniversal5.670374419 x 10^-8W m^-2 K^-4
Strong coupling constant
alpha_s(M_Z)Nuclear0.1179dimensionless
Vacuum electric permittivity
epsilon_0Electromagnetic8.8541878128 x 10^-12F/m
Vacuum magnetic permeability
mu_0Electromagnetic1.25663706212 x 10^-6N/A^2
von Klitzing constant
R_KElectromagnetic2.581280745 x 10^4Ohm
W boson mass
m_WNuclear80.377GeV/c^2
Wien displacement constant
bUniversal2.897771955 x 10^-3m K
Z boson mass
m_ZNuclear91.1876GeV/c^2
Values sourced from the 2018 CODATA recommended values of the fundamental physical constants and Planck 2018 cosmological parameters.
Constants marked “Exact (defined)” have fixed values as of the 2019 SI redefinition.