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 |