Table of physical constants

Table of universal constants

Quantity	Symbol	Value	Relative Standard Uncertainty
characteristic impedance of vacuum	$Z_0={\mu }_{0}c$	376.730 313 461... Ω	defined
electric constant (permittivity of free space)	${\epsilon }_0=1/({\mu }_0{c}^2)$	8.854 187 817... × 10-12F·m-1	defined
magnetic constant (permeability of free space)	${\mu }_0$	4π × 10-7 N·A-2 = 1.2566 370 614... × 10-6 N·A-2	defined
gravitational constant (Newtonian constant of gravitation)	$G$	6.6742(10) × 10-11m3·kg-1·s-2	1.5 × 10-4
Planck's constant	$h$	6.626 0693(11) × 10-34 J·s	1.7 × 10-7
Dirac's constant	$\hslash =h/(2\pi )$	1.054 571 68(18) × 10-34 J·s	1.7 × 10-7
speed of light in vacuum	$c$	299 792 458 m·s-1	defined

Table of electromagnetic constants

Quantity	Symbol	Value1 (SI units)	Relative Standard Uncertainty
Bohr magneton	${\mu }_B=e\hslash /2m_e$	927.400 949(80) × 10-26 J·T-1	8.6 × 10-8
conductance quantum	$G_0=2e^2/h$	7.748 091 733(26) × 10-5 S	3.3 × 10-9
Coulomb's constant	$\kappa =1/4\pi {\epsilon }_0$	8.987 742 438 × 109 N·m2C-2	defined
elementary charge	$e$	1.602 176 53(14) × 10-19 C	8.5 × 10-8
Josephson constant	$K_J=2e/h$	483 597.879(41) × 109 Hz· V-1	8.5 × 10-8
magnetic flux quantum	${\varphi }_0=h/2e$	2.067 833 72(18) × 10-15 Wb	8.5 × 10-8
nuclear magneton	${\mu }_N=e\hslash /2m_p$	5.050 783 43(43) × 10-27 J·T-1	8.6 × 10-8
resistance quantum	$R_0=h/2e^2$	12 906.403 725(43) Ω	3.3 × 10-9
von Klitzing constant	$R_K=h/e^2$	25 812.807 449(86) Ω	3.3 × 10-9

Table of atomic and nuclear constants

Quantity		Symbol	Value1 (SI units)	Relative Standard Uncertainty
Bohr radius		$a_0=\alpha /4\pi R_{\mathrm{\infty }}$	0.529 177 2108(18) × 10-10 m	3.3 × 10-9
Fermi coupling constant		$G_F/(\hslash c{)}^3$	1.166 39(1) × 10-5 GeV-2	8.6 × 10-6
fine structure constant		$\alpha ={\mu }_0{e}^{2}c/(2h)=e^2/(4\pi {\epsilon }_0\hslash c)$	7.297 352 568(24) × 10-3	3.3 × 10-9
Hartree energy		$E_h=2R_{\mathrm{\infty }}hc$	4.359 744 17(75) × 10-18 J	1.7 × 10-7
quantum of circulation		$h/2m_e$	3.636 947 550(24) × 10-4 m2 s-1	6.7 × 10-9
Rydberg constant		$R_{\mathrm{\infty }}={\alpha }^2{m}_{e}c/2h$	10 973 731.568 525(73) m-1	6.6 × 10-12
Thomson cross section		$(8\pi /3)r_e^2$	0.665 245 873(13) × 10-28 m2	2.0 × 10-8
Weinberg angle|weak mixing angle		${\sin }^2{\theta }_W=1-(m_W/m_Z{)}^2$	0.222 15(76)	3.4 × 10-3

Table of physico-chemical constants

Quantity		Symbol	Value1 (SI units)	Relative Standard Uncertainty
atomic mass constant (unified atomic mass unit)		$m_u=1u$	1.660 538 86(28) × 10-27 kg	1.7 × 10-7
Avogadro's number		$N_A,L$	6.0221417(10) × 1023	1.7 × 10-7
Boltzmann constant		$k=R/N_A$	1.380 6505(24) × 10-23 J·K-1	1.8 × 10-6
Faraday constant		$F=N_{A}e$	96 485.3383(83)C·mol-1	8.6 × 10-8
first radiation constant		$c_1=2\pi h{c}^2$	3.741 771 38(64) × 10-16 W·m2	1.7 × 10-7
	for spectral radiance	$c_{1L}$	1.191 042 82(20) × 10-16 W · m2 sr-1	1.7 × 10-7
Loschmidt constant	at $T$=273.15 K and $p$=101.325 kPa	$n_0=N_A/V_m$	2.686 7773(47) × 1025 m-3	1.8 × 10-6
gas constant		$R$	8.314 472(15) J·K-1·mol-1	1.7 × 10-6
molar Planck constant		$N_{A}h$	3.990 312 716(27) × 10-10 J · s · mol-1	6.7 × 10-9
molar volume of an ideal gas	at $T$=273.15 K and $p$=100 kPa	$V_m=RT/p$	22.710 981(40) × 10-3 m3 ·mol-1	1.7 × 10-6
	at $T$=273.15 K and $p$=101.325 kPa		22.413 996(39) × 10-3 m3 ·mol-1	1.7 × 10-6
Sackur-Tetrode constant	at $T$=1 K and $p$=100 kPa	$S_0/R=\frac{5}{2}$ $+\ln [(2\pi m_{u}kT/h^2{)}^{3/2}kT/p]$	-1.151 7047(44)	3.8 × 10-6
	at $T$=1 K and $p$=101.325 kPa		-1.164 8677(44)	3.8 × 10-6
second radiation constant		$c_2=hc/k$	1.438 7752(25) × 10-2 m·K	1.7 × 10-6
Stefan-Boltzmann constant		$\sigma =({\pi }^2/60)k^4/{\hslash }^3{c}^2$	5.670 400(40) × 10-8 W·m-2·K-4	7.0 × 10-6
Wien displacement law constant		$b=(hc/k)/$ 4.965 114 231...	2.897 7685(51) × 10-3 m · K	1.7 × 10-6

Table of adopted values

Quantity		Symbol	Value (SI units)	Relative Standard Uncertainty
conventional value of Josephson constant2		$K_{J-90}$	483 597.9 × 109 Hz · V-1	defined
conventional value of von Klitzing constant3		$R_{K-90}$	25 812.807 Ω	defined
molar mass	constant	$M_u=M({}^{12}\text{C})/12$	1 × 10-3 kg · mol-1	defined
	of carbon-12	$M({}^{12}\text{C})=N_{A}m({}^{12}\text{C})$	12 × 10-3 kg · mol−1	defined
standard acceleration of gravity (free fall on Earth)		$g_n$	9.806 65 m·s-2	defined
standard atmosphere		$\text{atm}$	101 325 Pa	defined

Notes

¹The values are given in the so-called concise form; the number in brackets is the standard uncertainty, which is the value multiplied by the relative standard uncertainty.
²This is the value adopted internationally for realizing representations of the volt using the Josephson effect.
³This is the value adopted internationally for realizing representations of the ohm using the quantum Hall effect.

See also

• Coupling constant
• Stellar constants
• Strong gravitational constant
• Vacuum constants