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)	$\varepsilon _{0}=1/(\mu _{0}c^{2})\,$	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	$\hbar =h/(2\pi )$	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	$\mu _{B}=e\hbar /2m_{e}$	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	$\kappa =1/4\pi \varepsilon _{0}\,$	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	$\phi _{0}=h/2e\,$	2.067 833 72(18) × 10^-15 Wb	8.5 × 10^-8
nuclear magneton	$\mu _{N}=e\hbar /2m_{p}$	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	$a_{0}=\alpha /4\pi R_{\infty }\,$	0.529 177 2108(18) × 10^-10 m	3.3 × 10^-9
Fermi coupling constant	$G_{F}/(\hbar c)^{3}$	1.166 39(1) × 10^-5 GeV^-2	8.6 × 10^-6
fine structure constant	$\alpha =\mu _{0}e^{2}c/(2h)=e^{2}/(4\pi \varepsilon _{0}\hbar c)\,$	7.297 352 568(24) × 10^-3	3.3 × 10^-9
Hartree energy	$E_{h}=2R_{\infty }hc\,$	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	$R_{\infty }=\alpha ^{2}m_{e}c/2h\,$	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)		$m_{u}=1\ u\,$	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		$c_{1}=2\pi hc^{2}\,$	3.741 771 38(64) × 10^-16 W·m²	1.7 × 10^-7
first radiation constant	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
molar volume of an ideal gas	at $T$ =273.15 K and $p$ =101.325 kPa	$V_{m}=RT/p\,$	22.413 996(39) × 10^-3 m³ ·mol^-1	1.7 × 10^-6
Sackur-Tetrode constant	at $T$ =1 K and $p$ =100 kPa	$S_{0}/R={\frac {5}{2}}$ $+\ln \left[(2\pi m_{u}kT/h^{2})^{3/2}kT/p\right]$	-1.151 7047(44)	3.8 × 10^-6
Sackur-Tetrode constant	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		$\sigma =(\pi ^{2}/60)k^{4}/\hbar ^{3}c^{2}$	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	$M_{u}=M(\,^{12}{\mbox{C}})/12$	1 × 10^-3 kg · mol^-1	defined
molar mass	of carbon-12	$M(\,^{12}{\mbox{C}})=N_{A}m(\,^{12}{\mbox{C}})$	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		${\mbox{atm}}\,$	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.