Reference
Scientific Constants
Search, copy, and learn — values defined by the SI and CODATA recommended values.
Speed of light in vacuum
c
2.997925e+8 m/s
Exact defined value; ultimate cosmic speed limit.
Gravitational constant
G
6.674300e-11 N·m²/kg²
Couples mass to gravitational force in Newton's law.
Planck constant
h
6.626070e-34 J·s
Defines the quantum of action.
Reduced Planck constant
ħ
1.054572e-34 J·s
h / 2π — appears in angular quantum equations.
Boltzmann constant
k_B
1.380649e-23 J/K
Relates thermal energy to temperature.
Elementary charge
e
1.602177e-19 C
Charge of a proton; defining constant of the SI.
Electron mass
mₑ
9.109384e-31 kg
Rest mass of an electron.
Proton mass
mₚ
1.672622e-27 kg
Rest mass of a proton.
Vacuum permittivity
ε₀
8.854188e-12 F/m
Electric constant of free space.
Vacuum permeability
μ₀
1.256637e-6 N/A²
Magnetic constant of free space.
Avogadro constant
Nₐ
6.022141e+23 1/mol
Particles per mole of substance.
Standard gravity
g
9.806650e+0 m/s²
Conventional value for Earth surface gravity.
Stefan–Boltzmann constant
σ
5.670374e-8 W/m²·K⁴
Total radiated power of a blackbody.