Values given below contain the (uncertainty) in the last two decimal places given in brackets. Values that do not have this uncertainty listed are exact. For example:

 mu = 1.66053873(13) x 10-27 kg mu = 1.66053873 x 10-27 kg Uncertainty in mu = 0.00000013 x 10-27 kg

NameSymbolValue
Atomic Mass Unit mu1.66053873(13) x 10-27 kg
Avogadro's Number NA6.02214199(47) x 1023 mol-1
Bohr Magneton B9.27400899(37) x 10-24 J T-1
Bohr Radius ao0.5291772083(19) x 10-10 m
Boltzmann's Constant k1.3806503(24) x 10-23 J K-1
Compton Wavelength c 2.426310215(18) x 10-12 m
Deuteron Mass md 3.34358309(26) x 10-27 kg
Electric Constant o8.854187817 x 10-12 F m-1
Electron Mass me9.10938188(72) x 10-31 kg
Electron-Volt eV1.602176462(63) x 10-19 J
Elementary Charge e1.602176462(63) x 10-19 C
Faraday Constant F9.64853415(39) x 104 C mol-1
Fine Structure Constant 7.297352533(27) x 10-3
Hartree Energy Eh4.35974381(34) x 10-18 J
Hydrogen Ground State 13.6057 eV
Josephson ConstantKj4.83597898(19) x 1014 Hz V-1
Magnetic Constant o4 x 10-7
Molar Gas Constant R8.314472(15) J K-1 mol-1
Natural Unit of Action 1.054571596(82) x 10-34 J s
Newtonian Constant of Gravitation G6.673(10) x 10-11 m3 kg-1 s-2
Neutron Mass mn1.67492716(13) x 10-27 kg
Nuclear Magneton n5.05078317(20) x 10-27 J T-1
Planck Constant h6.62606876(52) x 10-34 J s
h = 2
Planck Length lp1.6160(12) x 10-35 m
Planck Mass mp2.1767(16) x 10-8 kg
Planck Time tp5.3906(40) x 10-44 s
Proton Mass mP1.67262158(13) x 10-27 kg
Rydberg Constant RH 10 9.73731568549(83) x 105 m-1
Stefan Boltzmann Constant 5.670400(40) x 10-8 W m-2 K-4
Speed of Light in Vacuum c2.99792458 x 108 m s-1
Thompson Cross Section e0.665245854(15) x 10-28 m2
Wien Displacement Law Constant b 2.8977686(51) x 10-3 m K

Source:

CODATA Recommended Values of the Fundamental Physical Constants: 1998
by Peter J. Mohr and Barry N. Taylor
National Institute of standards and Technology, Gaithersburg, MD 20899-8401