Table of universal constants

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

Table of electromagnetic constants

Quantity	Symbol	Value1 (SI units)	Relative Standard Uncertainty
Bohr magneton	${\displaystyle \mu _{B}=e\hbar /2m_{e}}$	927.400 949(80) × 10-26 J·T-1	8.6 × 10-8
conductance quantum	${\displaystyle G_{0}=2e^{2}/h\,}$	7.748 091 733(26) × 10-5 S	3.3 × 10-9
Coulomb's constant	${\displaystyle \kappa =1/4\pi \varepsilon _{0}\,}$	8.987 742 438 × 109 N·m2C-2	defined
elementary charge	${\displaystyle e\,}$	1.602 176 53(14) × 10-19 C	8.5 × 10-8
Josephson constant	${\displaystyle K_{J}=2e/h\,}$	483 597.879(41) × 109 Hz· V-1	8.5 × 10-8
magnetic flux quantum	${\displaystyle \phi _{0}=h/2e\,}$	2.067 833 72(18) × 10-15 Wb	8.5 × 10-8
nuclear magneton	${\displaystyle \mu _{N}=e\hbar /2m_{p}}$	5.050 783 43(43) × 10-27 J·T-1	8.6 × 10-8
resistance quantum	${\displaystyle R_{0}=h/2e^{2}\,}$	12 906.403 725(43) Ω	3.3 × 10-9
von Klitzing constant	${\displaystyle R_{K}=h/e^{2}\,}$	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		${\displaystyle a_{0}=\alpha /4\pi R_{\infty }\,}$	0.529 177 2108(18) × 10-10 m	3.3 × 10-9
Fermi coupling constant		${\displaystyle G_{F}/(\hbar c)^{3}}$	1.166 39(1) × 10-5 GeV-2	8.6 × 10-6
fine structure constant		${\displaystyle \alpha =\mu _{0}e^{2}c/(2h)=e^{2}/(4\pi \varepsilon _{0}\hbar c)\,}$	7.297 352 568(24) × 10-3	3.3 × 10-9
Hartree energy		${\displaystyle E_{h}=2R_{\infty }hc\,}$	4.359 744 17(75) × 10-18 J	1.7 × 10-7
quantum of circulation		${\displaystyle h/2m_{e}\,}$	3.636 947 550(24) × 10-4 m2 s-1	6.7 × 10-9
Rydberg constant		${\displaystyle R_{\infty }=\alpha ^{2}m_{e}c/2h\,}$	10 973 731.568 525(73) m-1	6.6 × 10-12
Thomson cross section		${\displaystyle (8\pi /3)r_{e}^{2}}$	0.665 245 873(13) × 10-28 m2	2.0 × 10-8
Weinberg angle|weak mixing angle		${\displaystyle \sin ^{2}\theta _{W}=1-(m_{W}/m_{Z})^{2}\,}$	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)		${\displaystyle m_{u}=1\ u\,}$	1.660 538 86(28) × 10-27 kg	1.7 × 10-7
Avogadro's number		${\displaystyle N_{A},L\,}$	6.0221417(10) × 1023	1.7 × 10-7
Boltzmann constant		${\displaystyle k=R/N_{A}\,}$	1.380 6505(24) × 10-23 J·K-1	1.8 × 10-6
Faraday constant		${\displaystyle F=N_{A}e\,}$	96 485.3383(83)C·mol-1	8.6 × 10-8
first radiation constant		${\displaystyle c_{1}=2\pi hc^{2}\,}$	3.741 771 38(64) × 10-16 W·m2	1.7 × 10-7
	for spectral radiance	${\displaystyle c_{1L}\,}$	1.191 042 82(20) × 10-16 W · m2 sr-1	1.7 × 10-7
Loschmidt constant	at ${\displaystyle T}$=273.15 K and ${\displaystyle p}$=101.325 kPa	${\displaystyle n_{0}=N_{A}/V_{m}\,}$	2.686 7773(47) × 1025 m-3	1.8 × 10-6
gas constant		${\displaystyle R\,}$	8.314 472(15) J·K-1·mol-1	1.7 × 10-6
molar Planck constant		${\displaystyle N_{A}h\,}$	3.990 312 716(27) × 10-10 J · s · mol-1	6.7 × 10-9
molar volume of an ideal gas	at ${\displaystyle T}$=273.15 K and ${\displaystyle p}$=100 kPa	${\displaystyle V_{m}=RT/p\,}$	22.710 981(40) × 10-3 m3 ·mol-1	1.7 × 10-6
	at ${\displaystyle T}$=273.15 K and ${\displaystyle p}$=101.325 kPa		22.413 996(39) × 10-3 m3 ·mol-1	1.7 × 10-6
Sackur-Tetrode constant	at ${\displaystyle T}$=1 K and ${\displaystyle p}$=100 kPa	${\displaystyle S_{0}/R={\frac {5}{2}}}$ ${\displaystyle +\ln \left[(2\pi m_{u}kT/h^{2})^{3/2}kT/p\right]}$	-1.151 7047(44)	3.8 × 10-6
	at ${\displaystyle T}$=1 K and ${\displaystyle p}$=101.325 kPa		-1.164 8677(44)	3.8 × 10-6
second radiation constant		${\displaystyle c_{2}=hc/k\,}$	1.438 7752(25) × 10-2 m·K	1.7 × 10-6
Stefan-Boltzmann constant		${\displaystyle \sigma =(\pi ^{2}/60)k^{4}/\hbar ^{3}c^{2}}$	5.670 400(40) × 10-8 W·m-2·K-4	7.0 × 10-6
Wien displacement law constant		${\displaystyle b=(hc/k)/\,}$ 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		${\displaystyle K_{J-90}\,}$	483 597.9 × 109 Hz · V-1	defined
conventional value of von Klitzing constant3		${\displaystyle R_{K-90}\,}$	25 812.807 Ω	defined
molar mass	constant	${\displaystyle M_{u}=M(\,^{12}{\mbox{C}})/12}$	1 × 10-3 kg · mol-1	defined
	of carbon-12	${\displaystyle M(\,^{12}{\mbox{C}})=N_{A}m(\,^{12}{\mbox{C}})}$	12 × 10-3 kg · mol−1	defined
standard acceleration of gravity (free fall on Earth)		${\displaystyle g_{n}\,\!}$	9.806 65 m·s-2	defined
standard atmosphere		${\displaystyle {\mbox{atm}}\,}$	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.

See also

• Coupling constant
• Stellar constants
• Strong gravitational constant
• Vacuum constants
• Physics/Essays/Fedosin/Fine structure constant
• Physics/Essays/Fedosin/Gravitational characteristic impedance of free space
• Physics/Essays/Fedosin/Magnetic coupling constant
• Physics/Essays/Fedosin/Selfconsistent electromagnetic constants
• Physics/Essays/Fedosin/Selfconsistent gravitational constants
• Physics/Essays/Fedosin/Velocity circulation quantum