Physical Constants

symbol	name	value		unit
Physical Constants
c	speed of light in a vacuum	299,792,458		m/s
G	gravitational constant	6.67384	× 10⁻⁷	N m²/kg²
h	planck's constant	6.62606957 4.135667516	× 10⁻³⁴ × 10⁻¹⁵	J s eV s
hc		1.98644521 1239.84193	× 10⁻²⁵	J m eV nm
ℏ	h/2π reduced planck's constant dirac's constant	1.054571726 6.58211928	× 10⁻³⁴ × 10⁻¹⁶	J s eV s
ε₀	electric constant permitivitty of free space vacuum permitivitty	8.854187817	× 10⁻¹²	C²/N m²
μ₀	magnetic constant permeability of free space vacuum permeability	4π	× 10⁻⁷	T m/A
e	elementary charge	1.602176565	× 10⁻¹⁹	C
m_e	electron mass	9.10938291 0.510998928 0.00054857990946	× 10⁻³¹	kg MeV u
m_p	proton mass	1.672621777 938.272046 1.00727646812	× 10⁻²⁷	kg MeV u
m_n	neutron mass	1.674927351 939.565379 1.00866491600	× 10⁻²⁷	kg MeV u
m_u	atomic mass constant	1.660538921 931.494061 1	× 10⁻²⁷	kg MeV u
N_A	avogadro constant	6.02214129	× 10²³	1/mol
k	boltzmann's constant	1.3806488	× 10⁻²³	J/K
R	gas constant	8.3144621		J/mol K
σ	stefan-boltzmann constant	5.670373	× 10⁻⁸	W/m²K⁴
b	wien displacement constant	2.8977721 58.789254		mm/K GHz/K
g	standard gravity	9.80665		m/s²
atm	standard atmosphere	101,325		Pa
H₀	hubble constant*	70.8 2.29	× 10⁻¹⁸	km/s/Mpc s⁻¹
Source: NIST (*exception NASA)

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