 Values of Physical Constants

Approximate Numerical Values > s.a. anthropic principle; solar planets; types of particles; units.
* Table: To three or four significant digits, the values of some of the most commonly used physical constants are:

 Name Approximately Avogadro's number NA = 6.022 × 1023 mol−1 Boltzmann's constant kB = 1.381 × 10−16 erg/K = 1.381 × 10−23 J/K Electron charge e = 1.602 × 10−19 C Fine-structure constant α = 1/137 = 0.007299 Gas constant R = 8.314 J · mol/K Molar gas constant R = 1.987 cal/mol/K Magnetic permeability μ0 = 4π × 10−7 N/A2 Newton's constant G = 6.674 × 10−8 cm3/g/s2 Permittivity of the vacuum ε0 = 8.854 × 10−12 C2/N/m2 Planck's constant h = 6.62607 × 10−27 erg · s = 6.62607 × 10−34 J · s $$\hbar$$ = 1.05457 × 10−27 erg · s = 1.05457 × 10−34 J · s Rydberg constant R∞ = 1.097 × 105 cm−1 Speed of light c = 2.998 × 1010 m/s Stefan-Boltzmann constant σ = 5.670 × 10−8 W/m2/K4 Particle Property Approximately Electron mass me = 9.109 × 10−28 g = 511 keV/c2 Pion mass mπ = 139.6 MeV/c2 (π±), 135.0 MeV/c2 (π0) Kaon mass mK = 493.7 MeV/c2 (K±), 497.6 MeV/c2 (K0) Nucleon mass mN = 1.67 × 10−24 g

@ References: Mohr & Taylor RMP(05) [2002 values]; Mohr et al RMP(12)-a1203 [2010 values].
> Online resources: NIST website; Particle Data Group website and PDG Live website.