This table 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 as the data has been manually reformatted to HTML. The definitive source is NIST's site.
| Constant | Symbol | Value | Units |
| -------- | ------- | ------ | ------ |
| Speed of light in vacuum | c | 299792458 | m/s |
| Permeability of vacuum | mu0 | 1.25663706143592 x 10-06 | N/(A2) |
| Permittivity of vacuum | epsilon0 | 8.854187817 x 10-12 | F/m |
| Electrostatic Force Constant | 1/(4*pi*eo) | 8.987552 x 1009 | nt-m2/C2 |
| Constant of gravitation | G | 6.67259 x 10-11 +/- 8.5 x 10-15 | 1/(kg-s) |
| Planck constant | h | 6.6260755 x 10-34 +/- 4.0 x 10-40 | J-s |
| Planck constant in eV | h | 4.1356692 x 10-15 +/- 1.2 x 10-21 | eV s |
| Planck constant / (2 * pi) | h-bar | 1.05457266 x 10-34 +/- 6.3 x 10-41 | J-s |
| h-bar in eV | h-bar | 6.582122 x 10-16 +/- 2.0 x 10-22 | eV-s |
| Planck mass | none | 2.17671 x 10-08 +/- 1.4 x 10-12 | kg |
| Planck length | none | 1.61605 x 10-35 +/- 1.0 x 10-39 | m |
| Planck time | none | 5.39056 x 10-44 +/- 3.4 x 10-48 | s |
| Elementary charge | e | 1.60217733 x 10-19 +/- 4.9 x 10-26 | C |
| Magnetic flux quantum | Phi_0 | 2.06783461 x 10-15 +/- 6.1 x 10-22 | Wb |
| Josephson frequency-voltage quotient | none | 483597670000000 +/- 1.4x 1008 | 1/(V-s) |
| Quantized Hall conductance | none | 3.87404614 x 10-05 +/- 1.7 x 10-12 | Omega-1 |
| Quantized Hall resistance | none | 25812.8056 +/- 0.0012 | Omega |
| Bohr magneton | muB | 9.2740154 x 10-24 +/- 3.1 x 10-30 | J T-1 |
| Bohr magneton in eV | muB | 5.78838263 x 10-05 +/- 5.2 x 10-12 | eV/T |
| Bohr magneton in Hz | muB | 13996241800 +/- 4200 | 1/(T-s) |
| Bohr magneton in wavenumbers | muB | 46.686437 +/- 1.4 x 10-05 | 1/(m-T) |
| Bohr magneton in kelvins | muB | 0.6717099 +/- 5.7 x 10-06 | K/T |
| Nuclear magneton | none | 5.0507866 x 10-27 +/- 1.7 x 10-33 | J/T |
| Nuclear magneton in eV | none | 3.15245166 x 10-08 +/- 2.8 x 10-15 | eV/T |
| Nuclear magneton in Hz | none | 7622591.4 +/- 2.3 | 1/(T-s) |
| Nuclear magneton in wavenumbers | none | 0.0254262281 +/- 7.7 x 10-09 | 1/(m-T) |
| Nuclear magneton in kelvins | none | 0.0003658246 +/- 3.1 x 10-09 | K/T |
| Fine structure constant | alpha | 0.00729735308 +/- 3.3 x 10-10 | |
| Inverse fine structure constant | 1/alpha | 137.0359895 +/- 6.1 x 10-06 | |
| Rydberg constant | Ry | 10973731.534 +/- 0.013 | m-1 |
| Rydberg constant in Hz | Ry | 3.2898419499 x 1015 +/- 3.9 x 1006 | 1/s |
| Rydberg constant in joules | Ry | 2.1798741 x 10-18 +/- 1.3 x 10-24 | J |
| Rydberg constant in eV | Ry | 13.6056981 +/- 4.0 x 10-06 | eV |
| Bohr radius | a0 | 5.29177249 x 10-11 +/- 2.4 x 10-18 | m |
| Hartree energy | Eh | 4.3597482 x 10-18 +/- 2.6 x 10-24 | J |
| Hartree energy in eV | Eh | 2.72113961 +/- 8.1 x 10-05 | eV |
| Quantum of circulation | none | 0.000363694807 +/- 3.3 x 10-11 | m2/s |
| Electron mass | none | 9.1093897 x 10-31 +/- 5.4 x 10-37 | kg |
| Electron mass in u | none | 0.000548579903 +/- 1.3 x 10-11 | u |
| Electron mass in eV | none | 510999.06 +/- 0.15 | eV |
| Electron-muon mass ratio | none | 0.00483633218 +/- 7.1 x 10-10 | |
| Electron-proton mass ratio | none | 0.000544617013 +/- 1.1 x 10-11 | |
| Electron-deuteron mass ratio | none | 0.000272443707 +/- 6 x 10-12 | |
| Electron-alpha-particle mass ratio | none | 0.000137093354 +/- 3 x 10-12 | |
| Electron specific charge | none | -175881962000 +/- -53000 | C/kg |
| Electron molar mass | none | 5.48579903 x 10-07 +/- 1.3 x 10-14 | kg/mol |
| Electron Compton wavelength | lambdaC | 2.42631058 x 10-12 +/- 2.2 x 10-19 | m |
| Electron Compton wavelength / 2 pi | lambda-barC | 3.86159323 x 10-13 +/- 3.5 x 10-20 | m |
| Electron classical radius | re | 2.81794092 x 10-15 +/- 3.8 x 10-22 | m |
| Electron Thomson cross section | sigmae | 6.6524616 x 10-29 +/- 1.8 x 10-35 | m2 |
| Electron magnetic moment | none | 9.2847701 x 10-24 +/- 3.1 x 10-30 | J/T |
| Electron magnetic moment Bohr magnetons | none | 1.001159652193 +/- 1.0 x 10-11 | |
| Electron magnetic moment in nuclear magnetons | none | 1838.282 +/- 3.7 x 10-05 | |
| Electron magnetic moment anomaly | ae | 0.001159652193 +/- 1.0 x 10-11 | |
| Electron g-factor | ge | 2.002319304386 +/- 2.0 x 10-11 | |
| Electron-muon magnetic moment ratio | none | 206.766967 +/- 3.0 x 10-05 | |
| Electron-proton magnetic moment ratio | none | 658.2106881 +/- 6.6 x 10-06 | |
| Muon mass | none | 1.8835327 x 10-28 +/- 1.1 x 10-34 | kg |
| Muon mass in u | none | 0.113428913 +/- 1.7 x 10-08 | u |
| Muon mass in eV | none | 105658389 +/- 34 | eV |
| Muon-electron mass ratio | none | 206.768262 +/- 3.0 x 10-05 | |
| Muon molar mass | none | 0.000113428913 +/- 1.7 x 10-11 | kg mol-1 |
| Muon magnetic moment | none | 4.4904514 x 10-26 +/- 1.5 x 10-32 | J T-1 |
| Muon magnetic moment in Bohr magnetons | none | 0.00484197097 +/- 7.1 x 10-10 | |
| Muon magnetic moment nuclear magnetons | none | 8.8905981 +/- 1.3 x 10-06 | |
| Muon magnetic moment anomaly | amu | 0.001165923 +/- 8.4 x 10-09 | |
| Muon g-factor | gmu | 2.002331846 +/- 1.7 x 10-08 | |
| Muon-proton magnetic moment ratio | none | 3.18334547 +/- 4.7 x 10-07 | |
| Proton radius from electron difussion | none | 8.62 x 10-16 +/- 0.02 | m |
| Proton mass | none | 1.6726231 x 10-27 +/- 1.0 x 10-33kg | |
| Proton mass in u | none | 1.00727647 +/- 1.2 x 10-08 | u |
| Proton mass in eV | none | 938272310 +/- 280 | eV |
| Proton-electron mass ratio | none | 1836.152701 +/- 3.7 x 10-05 | |
| Proton-muon mass ratio | none | 8.8802444 +/- 1.3 x 10-06 | |
| Proton specific charge | none | 95788309 +/- 29 | C kg-1 |
| Proton molar mass | none | 0.00100727647 +/- 1.2 x 10-11 | kg mol-1 |
| Proton Compton wavelength | lambdaC,p | 1.32141002 x 10-15 +/- 1.2 x 10-22 | m |
| Proton magnetic moment | none | 1.41060761 x 10-26 +/- 4.7 x 10-33 | J T-1 |
| Proton magnetic moment Bohr magnetons | none | 0.001521032202 +/- 1.5 x 10-11 | |
| Proton magnetic moment nclr magnetons | none | 2.792847386 +/- 6.3 x 10-08 | |
| Proton gyromagnetic ratio | gammap | 267522128 +/- 81 | T-1 s-1 |
| Neutron mass | none | 1.6749286 x 10-27 +/- 1.0 x 10-33 | kg |
| Neutron mass in u | none | 1.008664904 +/- 1.4 x 10-08 | u |
| Neutron mass in eV | none | 939565630 +/- 280 | eV |
| Neutron-electron mass ratio | none | 1838.683662 +/- 4.0 x 10-05 | |
| Neutron-proton mass ratio | none | 1.001378404 +/- 9 x 10-09 | |
| Neutron molar mass | none | 1.008664904 +/- 1.4 x 10-14 | kg mol-1 |
| Neutron Compton wavelength | lambdaC,n | 1.3195911 x 10-15 +/- 1.2 x 10-22 | m |
| Neutron magnetic moment | none | 9.6623707 x 10-27 +/- 4.0 x 10-33 | J T-1 |
| Neutron magnetic moment Bohr magnetons | none | 0.00104187563 +/- 2.5 x 10-10 | |
| Neutron magnetic moment nuclear magnetons | none | 1.91304275 +/- 4.5 x 10-07 | |
| Neutron-electron magnetic moment ratio | none | 0.00104066882 +/- 2.5 x 10-10 | |
| Neutron-proton magnetic moment ratio | none | 0.68497934 +/- 1.6 x 10-07 | |
| Deuteron mass | none | 3.343586 x 10-27 +/- 2.0 x 10-33 | kg |
| Deuteron mass in u | none | 2.013553214 +/- 2.4 x 10-08 | u |
| Deuteron mass in eV | none | 1875613390 +/- 570 | eV |
| Deuteron-electron mass ratio | none | 3670.483014 +/- 7.5 x 10-05 | |
| Deuteron-proton mass ratio | none | 1.999007496 +/- 6 x 10-09 | |
| Deuteron molar mass | none | 0.002013553214 +/- 2.4 x 10-11 | kg mol-1 |
| Deuteron magnetic moment | mud | 4.3307375 x 10-27 +/- 1.5 x 10-33 | J T-1 |
| Deuteron magnetic moment Bohr magnetons | none | 0.0004669754479 +/- 9.1 x 10-12 | |
| Deuteron mgntc moment nuclear magnetons | none | 0.85743823 +/- 2.4 x 10-08 | |
| Deuteron-electron magnetic moment ratio | none | 0.000466434546 +/- 9.1 x 10-12 | |
| Deuteron-proton magnetic moment ratio | none | 0.3070122035 +/- 5.1 x 10-09 | |
| Avagadro constant | NA | 6.0221367x 1023 +/- 3.6x 1017 | mol-1 |
| Faraday constant | F | 96485.309 +/- 0.029 | C mol-1 |
| Molar Planck constant | none | 3.99031323 x 10-10 +/- 3.6 x 10-17 | J s mol-1 |
| Molar gas constant | R | 8.31451 +/- 7.0 x 10-05 | J mol-1 K-1 |
| Boltzmann constant | k | 1.380658 x 10-23 +/- 1.2 x 10-28 | J K-1 |
| Boltzmann constant in eV | k | 8.617385 x 10-05 +/- 7.3 x 10-10e | V K-1 |
| Boltzmann constant in Hz | k | 20836740000 +/- 180000 | K-1 s-1 |
| Boltzmann constant in wavenumbers | k | 69.50387 +/- 0.00059 | m-1 K-1 |
| Molar volume ideal gas, STP | Vm | 0.0224141 +/- 1.9 x 10-07 | m3 mol-1 |
| Loschmidt constant | n0 | 2.686763x 1025 +/- 2.3x 1020 | m-3 |
| Stefan-Boltzmann constant | sigma | 5.67051 x 10-08 +/- 1.9 x 10-12 | W m-2 K-4 |
| First radiation constant | c1 | 3.7417749 x 10-16 +/- 2.2 x 10-22 | W m2 |
| Second radiation constant | c2 | 0.01438769 +/- 1.2 x 10-07 | m K |
| Wien displacement law constant | b | 0.002897756 +/- 2.4 x 10-08 | m K |
| Electron volt | eV | 1.60217733 x 10-19 +/- 4.9 x 10-26 | J |
| Atomic mass unit | u | 1.6605402 x 10-27 +/- 1.0 x 10-33 | kg |
| Atomic mass unit in eV | none | 931494320 +/- 280 eV | |
| Standard atmosphere | atm | 101325 | Pa |
| Std accel gravity | none | 9.80665m | s-2 |
| BIPM-maintained ohm, | Omega_B185 | 1-1.563 x 10-6 +/- 5.0 x 10-08O | mega |
| Lattice spacing of Si in vacuum, 295.65 K | a | 5.4310196 x 10-10 +/- 1.1 x 10-16 | m |
| Lattice spacing Si 220 plane | d_220 | 1.9201554 x 10-10 +/- 4.0 x 10-17 | m |
| Molar volume of Si | VmSi | 1.20588179 x 10-05 +/- 8.9 x 10-12 | m3 mol-1 |
| Radiation density constant | a | 7.564 x 10-16 | J M^-3 K^-4 |
| Mass of the Sun | Msolar | 1.9891x 1030 | Kg. |
| Mass of the Earth | Mearth | 5.9724 x 1024 | Kg. |
| Equatorial radius of the earth | none | 6.378137 x 106 | m |
| Polar radius of the earth | none | 6.356752 x 106 | m |
| Astronomical unit | au | 1.4959787066 x 1011 | m |
| Mean radius of Mercury's orbit: | none | 5.7909096376 x 1010 | m |
| Sideral period of Mercury: | none | 87.96 | days |
| Atmospheric pressure at sea level (avarage): | none | 101325 | Pascals | Solar radius: | average | 6.97 x 108 | m |