Table of Fundamental Physical Constants

This data is derived from the 1986 CODATA recommended values of the fundamental physical constants. It is not intended to be an authoritative source: typographical errors are possible and the data has been reformatted. You can find the more complete information from the NIST at https://physics.nist.gov/PhysRefData/codata86/codata86.html

#ConstantSymbolValueUnits
1Speed of light in vacuum(c)299792458m s-1
2Permeability of vacuum(mu_0)1.25663706143592e-06N A-2
3Permittivity of vacuum(epsilon_0)8.854187817e-12F m-1
4Newtonian constant of gravitation(G)6.67259e-11 ± 8.5e-15m3 kg-1 s-2
5Planck constant(h)6.6260755e-34 ± 4.0e-40J s
6Planck constant in eV 4.1356692e-15 ± 1.2e-21eV s
7h-bar(h-bar)1.05457266e-34 ± 6.3e-41J s
8h-bar in eV 6.582122e-16 ± 2.0e-22eV s
9Planck mass(m_p)2.17671e-08 ± 1.4e-12kg
10Planck length(l_p)1.61605e-35 ± 1.0e-39m
11Planck time(t_p)5.39056e-44 ± 3.4e-48s
12Elementary charge(e)1.60217733e-19 ± 4.9e-26C
13Magnetic flux quantum(Phi_0)2.06783461e-15 ± 6.1e-22Wb
14Josephson frequency-voltage quotient 483597670000000 ± 1.4e+08V-1 s-1
15Quantized Hall conductance 3.87404614e-05 ± 1.7e-12Omega-1
16Quantized Hall resistance(R_H)25812.8056 ± 0.0012Omega
17Bohr magneton(mu_B)9.2740154e-24 ± 3.1e-30J T-1
18Bohr magneton in eV 5.78838263e-05 ± 5.2e-12eV T-1
19Bohr magneton in Hz 13996241800 ± 4200T-1 s-1
20Bohr magneton in wavenumbers 46.686437 ± 1.4e-05m-1 T-1
21Bohr magneton in kelvins 0.6717099 ± 5.7e-06K T-1
22Nuclear magneton(mu_N)5.0507866e-27 ± 1.7e-33J T-1
23Nuclear magneton in eV 3.15245166e-08 ± 2.8e-15eV T-1
24Nuclear magneton in Hz 7622591.4 ± 2.3T-1 s-1
25Nuclear magneton in wavenumbers 0.0254262281 ± 7.7e-09m-1 T-1
26Nuclear magneton in kelvins 0.0003658246 ± 3.1e-09K T-1
27Fine structure constant(alpha)0.00729735308 ± 3.3e-10 
28Inverse fine structure constant 137.0359895 ± 6.1e-06 
29Rydberg constant(Ry)10973731.534 ± 0.013m-1
30Rydberg constant in Hz 3.2898419499e+15 ± 3.9e+06s-1
31Rydberg constant in joules 2.1798741e-18 ± 1.3e-24J
32Rydberg constant in eV 13.6056981 ± 4.0e-06eV
33Bohr radius(a_0)5.29177249e-11 ± 2.4e-18m
34Hartree energy(E_h)4.3597482e-18 ± 2.6e-24J
35Hartree energy in eV 27.2113961 ± 8.1e-06eV
36Quantum of circulation 0.000363694807 ± 3.3e-11m2 s-1
37Electron mass(m_e)9.1093897e-31 ± 5.4e-37kg
38Electron mass in u 0.000548579903 ± 1.3e-11u
39Electron mass in eV 510999.06 ± 0.15eV
40Electron-muon mass ratio 0.00483633218 ± 7.1e-10 
41Electron-proton mass ratio 0.000544617013 ± 1.1e-11 
42Electron-deuteron mass ratio 0.000272443707 ± 6e-12 
43Electron-alpha-particle mass ratio 0.000137093354 ± 3e-12 
44Electron specific charge -175881962000 ± -53000C kg-1
45Electron molar mass 5.48579903e-07 ± 1.3e-14kg mol-1
46Electron Compton wavelength(lambda_C)2.42631058e-12 ± 2.2e-19m
47Electron Compton wavelength over 2 pi(lambda-bar_C)3.86159323e-13 ± 3.5e-20m
48Electron classical radius(r_e)2.81794092e-15 ± 3.8e-22m
49Electron Thomson cross section(sigma_e)6.6524616e-29 ± 1.8e-35m2
50Electron magnetic moment 9.2847701e-24 ± 3.1e-30J T-1
51Electron magnetic moment in Bohr magnetons 1.001159652193 ± 1.0e-11 
52Electron magnetic moment in nuclear magnetons 1838.282 ± 3.7e-05 
53Electron magnetic moment anomaly(a_e)0.001159652193 ± 1.0e-11 
54Electron g-factor(g_e)2.002319304386 ± 2.0e-11 
55Electron-muon magnetic moment ratio 206.766967 ± 3.0e-05 
56Electron-proton magnetic moment ratio 658.2106881 ± 6.6e-06 
57Muon mass 1.8835327e-28 ± 1.1e-34kg
58Muon mass in u 0.113428913 ± 1.7e-08u
59Muon mass in eV 105658389 ± 34eV
60Muon-electron mass ratio 206.768262 ± 3.0e-05 
61Muon molar mass 0.000113428913 ± 1.7e-11kg mol-1
62Muon magnetic moment 4.4904514e-26 ± 1.5e-32J T-1
63Muon magnetic moment in Bohr magnetons 0.00484197097 ± 7.1e-10 
64Muon magnetic moment in nuclear magnetons 8.8905981 ± 1.3e-06 
65Muon magnetic moment anomaly(a_mu)0.001165923 ± 8.4e-09 
66Muon g-factor(g_mu)2.002331846 ± 1.7e-08 
67Muon-proton magnetic moment ratio 3.18334547 ± 4.7e-07 
68Proton mass(m_p)1.6726231e-27 ± 1.0e-33kg
69Proton mass in u 1.00727647 ± 1.2e-08u
70Proton mass in eV 938272310 ± 280eV
71Proton-electron mass ratio 1836.152701 ± 3.7e-05 
72Proton-muon mass ratio 8.8802444 ± 1.3e-06 
73Proton specific charge 95788309 ± 29C kg-1
74Proton molar mass 0.00100727647 ± 1.2e-11kg mol-1
75Proton Compton wavelength(lambda_C,p)1.32141002e-15 ± 1.2e-22m
76Proton magnetic moment 1.41060761e-26 ± 4.7e-33J T-1
77Proton magnetic moment in Bohr magnetons 0.001521032202 ± 1.5e-11 
78Proton magnetic moment in nuclear magnetons 2.792847386 ± 6.3e-08 
79Diamagnetic shielding correction for protons (H_2 O, spherical sample, 298.15 K)(sigma_H2O)2.5689e-05 ± 1.5e-08 
80Shielded proton moment (H_2 O, spherical sample, 298.15 K)(mu_p’)1.41057138e-26 ± 4.7e-33J T-1
81Shielded proton moment in Bohr magnetons 0.001520993129 ± 1.7e-11 
82Shielded proton moment in nuclear magnetons 2.792775642 ± 6.4e-08 
83Proton gyromagnetic ratio(gamma_p)267522128 ± 81T-1 s-1
84 (gamma_p)42577469 ± 13T-1 s-1
85Proton gyromagnetic ratio, uncorrected (H_2 O, spherical sample, 298.15 K)(gamma_p’)267515255 ± 81T-1 s-1
86 (gamma_p’/2pi)42576375 ± 13T-1 s-1
87Neutron mass(m_n)1.6749286e-27 ± 1.0e-33kg
88Neutron mass in u 1.008664904 ± 1.4e-08u
89Neutron mass in eV 939565630 ± 280eV
90Neutron-electron mass ratio 1838.683662 ± 4.0e-05 
91Neutron-proton mass ratio 1.001378404 ± 9e-09 
92Neutron molar mass 0.001008664904 ± 1.4e-11kg mol-1
93Neutron Compton wavelength(lambda_C,n)1.3195911e-15 ± 1.2e-22m
94Neutron magnetic moment 9.6623707e-27 ± 4.0e-33J T-1
95Neutron magnetic moment in Bohr magnetons 0.00104187563 ± 2.5e-10 
96Neutron magnetic moment in nuclear magnetons 1.91304275 ± 4.5e-07 
97Neutron-electron magnetic moment ratio 0.00104066882 ± 2.5e-10 
98Neutron-proton magnetic moment ratio 0.68497934 ± 1.6e-07 
99Deuteron mass(m_d)3.343586e-27 ± 2.0e-33kg
100Deuteron mass in u 2.013553214 ± 2.4e-08u
101Deuteron mass in eV 1875613390 ± 570eV
102Deuteron-electron mass ratio 3670.483014 ± 7.5e-05 
103Deuteron-proton mass ratio 1.999007496 ± 6e-09 
104Deuteron molar mass 0.002013553214 ± 2.4e-11kg mol-1
105Deuteron magnetic moment(mu_d)4.3307375e-27 ± 1.5e-33J T-1
106Deuteron magnetic moment in Bohr magnetons 0.0004669754479 ± 9.1e-12 
107Deuteron magnetic moment in nuclear magnetons 0.85743823 ± 2.4e-08 
108Deuteron-electron magnetic moment ratio 0.000466434546 ± 9.1e-12 
109Deuteron-proton magnetic moment ratio 0.3070122035 ± 5.1e-09 
110Avagadro constant(N_A)6.0221367e+23 ± 3.6e+17mol-1
111Atomic mass constant(m_u)1.6605402e-27 ± 1.0e-33kg
112Atomic mass constant in eV 931494320 ± 280eV
113Faraday constant(F)96485.309 ± 0.029C mol-1
114Molar Planck constant 3.99031323e-10 ± 3.6e-17J s mol-1
115 (N_A hc)0.11962658 ± 1.1e-07J m mol-1
116Molar gas constant(R)8.31451 ± 7.0e-05J mol-1 K-1
117Boltzmann constant(k)1.380658e-23 ± 1.2e-28J K-1
118Boltzmann constant in eV 8.617385e-05 ± 7.3e-10eV K-1
119Boltzmann constant in Hz 20836740000 ± 180000K-1 s-1
120Boltzmann constant in wavenumbers 69.50387 ± 0.00059m-1 K-1
121Molar volume (ideal gas), STP(V_m)0.0224141 ± 1.9e-07m3 mol-1
122Loschmidt constant(n_0)2.686763e+25 ± 2.3e+20m-3
123Stefan-Boltzmann constant(sigma)5.67051e-08 ± 1.9e-12W m-2 K-4
124First radiation constant(c_1)3.7417749e-16 ± 2.2e-22W m2
125Second radiation constant(c_2)0.01438769 ± 1.2e-07m K
126Wien displacement law constant(b)0.002897756 ± 2.4e-08m K
127Electron volt(eV)1.60217733e-19 ± 4.9e-26J
128Atomic mass unit(u)1.6605402e-27 ± 1.0e-33kg
129Standard atmosphere(atm)101325Pa
130Standard acceleration of gravity(g_n)9.80665m s-2
131BIPM-maintained ohm, Omega_69-B1 as of 1 Jan 85(Omega_B185)1-1.563e-6 ± 5.0e-08Omega
132Drift rate of Omega_69-B1(dOmega_69-B1/dt)-0.0566 ± -0.0015muOmega/yr
133BIPM-maintained volt 483 694 GHz(h/2e)(V_76-B1)1-7.59e-6 ± 3.0e-07V
134BIPM maintained ampere A_BIPM(A_B185)1-6.03e-6 ± 3.0e-07A
135Cu x-unit:(xu(CuKalpha1))1.00207789e-13 ± 7.0e-20m
136Mo x-unit:(xu(MoKalpha1))1.00209938e-13 ± 4.5e-20m
137AA *:(AAngstrom-star)1.00001481e-10 ± 9.2e-17m
138Lattice spacing of Si (in vacuum, 295.65 K)(a)5.4310196e-10 ± 1.1e-16m
139Lattice spacing Si (220) plane(d_220)1.9201554e-10 ± 4.0e-17m
140Molar volume of Si(V_m(Si))1.20588179e-05 ± 8.9e-12m3 mol-1