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 http://physics.nist.gov/PhysRefData/codata86/codata86.html.

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