
Constant Name Definition Mass of an electron m_{e} = 9.1093897 × 10^{31} kg Mass of a proton m_{p} = 1.6726231 × 10^{27} kg Mass of a neutron m_{n} = 1.6749286 × 10^{27} kg Elementary charge e = 1.60217653 × 10^{−19} C Unified atomic mass unit 1 u = 1.66056×10^{−27} kg Constant in Coulomb's law K = 8.988 × 10^{9} N·m^{2}·kg^{2}

Constant Name Definition Permeability of vacuum μ_{0} = 4π × 10^{−7}T^{2}·m^{3}·J^{1} = 12.566370614 × 10^{−7} T^{2}·m^{3}·J^{1} Permittivity of vacuum ε_{0} = 1/(μ_{0}c^{2}) = 8.854187817 × 10^{−12} C^{2}·J^{1}·m^{1}

Constant Name Definition Molar gas constant R = 8.314472 J·mol^{1}·K^{1} Molar Volume V_{mol} = 22.41383 m^{3}·kmol^{1} Avogadro constant N_{A} = 6.0221415 × 10^{23} mol^{1}

Constant Name Definition Absolute zero temperature 0 K = −273.15 °C Speed of light in vacuum c = 2.99792458 × 10^{8} m·s^{1} Newtonian constant of gravitation G = 6.6742 × 10^{−11} m^{3}·kg^{1} s^{2} Planck constant h = 6.6260693 × 10^{−34} J·Hz^{1} = 4.136 × 10^{15} eV·s; Planck constant over = 1.05457148 × 10^{−34} J·s Boltzmann's constant k = 1.3806505 × 10^{−23} J K^{1} StefanBoltzmann constant σ = 5.670400 × 10^{−8} W·m^{2}·K^{4} Bohr radius a_{0} = 5.292 × 10^{−11} m Electron radius r_{e} = 2.81792 × 10^{15} Fine structure constant α = e^{2}/(2ε_{0}hc) = 1/137.0359895 = 7.2974 × 10^{3} Thomson crosssection σ_{e} = 6.652 × 10^{−29} m^{2}
Some values from the 2002 CODATA recommended values of the Fundamental Physical Constants. See Constants Information at NIST.