ConstantID

All 355 constants

Every value in the CODATA 2022 adjustment, as NIST publishes it. Uncertainties are in parentheses and apply to the last digits: 6.674 30(15) means 6.674 30 ± 0.000 15.

SymbolQuantityValue (uncertainty)UnitRel. unc.
mαAlpha particle mass 6.644 657 3450(21) × 10−27kg3.2 × 10−10
mαc2Alpha particle mass energy equivalent 5.971 920 1997(19) × 10−10J3.2 × 10−10
mαc2Alpha particle mass energy equivalent in MeV 3727.379 4118(12)MeV3.2 × 10−10
mαAlpha particle mass in u 4.001 506 179 129(62)u1.5 × 10−11
M(α)Alpha particle molar mass 4.001 506 1833(12) × 10−3kg mol−13.0 × 10−10
Ar(α)Alpha particle relative atomic mass 4.001 506 179 129(62)1.5 × 10−11
rαAlpha particle rms charge radius 1.6785(21) × 10−15m1.3 × 10−3
mα/meAlpha particle-electron mass ratio 7294.299 541 71(17)2.3 × 10−11
mα/mpAlpha particle-proton mass ratio 3.972 599 690 252(70)1.8 × 10−11
Å*Angstrom star 1.000 014 95(90) × 10−10m9.0 × 10−7
muAtomic mass constant 1.660 539 068 92(52) × 10−27kg3.1 × 10−10
muc2Atomic mass constant energy equivalent 1.492 418 087 68(46) × 10−10J3.1 × 10−10
muc2Atomic mass constant energy equivalent in MeV 931.494 103 72(29)MeV3.1 × 10−10
(1u)Atomic mass unit-electron volt relationship 9.314 941 0372(29) × 108eV3.1 × 10−10
(1u)Atomic mass unit-hartree relationship 3.423 177 6922(11) × 107Eh3.2 × 10−10
(1u)Atomic mass unit-hertz relationship 2.252 342 721 85(70) × 1023Hz3.1 × 10−10
(1u)Atomic mass unit-inverse meter relationship 7.513 006 6209(23) × 1014m−13.1 × 10−10
(1u)Atomic mass unit-joule relationship 1.492 418 087 68(46) × 10−10J3.1 × 10−10
(1u)Atomic mass unit-kelvin relationship 1.080 954 020 67(34) × 1013K3.1 × 10−10
(1u)Atomic mass unit-kilogram relationship 1.660 539 068 92(52) × 10−27kg3.1 × 10−10
e3a03/Eh2Atomic unit of 1st hyperpolarizability 3.206 361 2996(15) × 10−53C3 m3 J−24.7 × 10−10
e4a04/Eh3Atomic unit of 2nd hyperpolarizability 6.235 379 9735(39) × 10−65C4 m4 J−36.3 × 10−10
ℏAtomic unit of action 1.054 571 817… × 10−34J sexact
eAtomic unit of charge 1.602 176 634 × 10−19Cexact
e/a03Atomic unit of charge density 1.081 202 386 77(51) × 1012C m−34.7 × 10−10
eEh/ℏAtomic unit of current 6.623 618 237 5082(72) × 10−3A1.1 × 10−12
ea0Atomic unit of electric dipole moment 8.478 353 6198(13) × 10−30C m1.5 × 10−10
Eh/ea0Atomic unit of electric field 5.142 206 751 12(80) × 1011V m−11.6 × 10−10
Eh/ea02Atomic unit of electric field gradient 9.717 362 4424(30) × 1021V m−23.1 × 10−10
e2a02/EhAtomic unit of electric polarizability 1.648 777 272 12(51) × 10−41C2 m2 J−13.1 × 10−10
Eh/eAtomic unit of electric potential 27.211 386 245 981(30)V1.1 × 10−12
ea02Atomic unit of electric quadrupole moment 4.486 551 5185(14) × 10−40C m23.1 × 10−10
EhAtomic unit of energy 4.359 744 722 2060(48) × 10−18J1.1 × 10−12
Eh/a0Atomic unit of force 8.238 723 5038(13) × 10−8N1.6 × 10−10
a0Atomic unit of length 5.291 772 105 44(82) × 10−11m1.5 × 10−10
ℏe/meAtomic unit of magnetic dipole moment 1.854 802 013 15(58) × 10−23J T−13.1 × 10−10
ℏ/ea02Atomic unit of magnetic flux density 2.350 517 570 77(73) × 105T3.1 × 10−10
e2a02/meAtomic unit of magnetizability 7.891 036 5794(49) × 10−29J T−26.2 × 10−10
meAtomic unit of mass 9.109 383 7139(28) × 10−31kg3.1 × 10−10
ℏ/a0Atomic unit of momentum 1.992 851 915 45(31) × 10−24kg m s−11.6 × 10−10
e2/a0EhAtomic unit of permittivity 1.112 650 056 20(17) × 10−10F m−11.5 × 10−10
ℏ/EhAtomic unit of time 2.418 884 326 5864(26) × 10−17s1.1 × 10−12
a0Eh/ℏAtomic unit of velocity 2.187 691 262 16(34) × 106m s−11.6 × 10−10
NAAvogadro constant 6.022 140 76 × 1023mol−1exact
μBBohr magneton 9.274 010 0657(29) × 10−24J T−13.1 × 10−10
μBBohr magneton in eV/T 5.788 381 7982(18) × 10−5eV T−13.1 × 10−10
μB/hBohr magneton in Hz/T 1.399 624 491 71(44) × 1010Hz T−13.1 × 10−10
μB/hcBohr magneton in inverse meter per tesla 46.686 447 719(15)m−1 T−13.2 × 10−10
μB/kBohr magneton in K/T 0.671 713 814 72(21)K T−13.1 × 10−10
a0Bohr radius 5.291 772 105 44(82) × 10−11m1.5 × 10−10
kBoltzmann constant 1.380 649 × 10−23J K−1exact
kBoltzmann constant in eV/K 8.617 333 262… × 10−5eV K−1exact
k/hBoltzmann constant in Hz/K 2.083 661 912… × 1010Hz K−1exact
k/hcBoltzmann constant in inverse meter per kelvin 69.503 480 04…m−1 K−1exact
Z0Characteristic impedance of vacuum 376.730 313 412(59)Ω1.6 × 10−10
reClassical electron radius 2.817 940 3205(13) × 10−15m4.6 × 10−10
λCCompton wavelength 2.426 310 235 38(76) × 10−12m3.1 × 10−10
G0Conductance quantum 7.748 091 729… × 10−5Sexact
A90Conventional value of ampere-90 1.000 000 088 87…Aexact
C90Conventional value of coulomb-90 1.000 000 088 87…Cexact
F90Conventional value of farad-90 0.999 999 982 20…Fexact
H90Conventional value of henry-90 1.000 000 017 79…Hexact
KJ-90Conventional value of Josephson constant 483 597.9 × 109Hz V−1exact
Ω90Conventional value of ohm-90 1.000 000 017 79…Ωexact
V90Conventional value of volt-90 1.000 000 106 66…Vexact
RK-90Conventional value of von Klitzing constant 25 812.807Ωexact
W90Conventional value of watt-90 1.000 000 195 53…Wexact
xu(Cu Kα1)Copper x unit 1.002 076 97(28) × 10−13m2.8 × 10−7
gdDeuteron g factor 0.857 438 2335(22)2.6 × 10−9
μdDeuteron magnetic moment 4.330 735 087(11) × 10−27J T−12.5 × 10−9
μd/μBDeuteron magnetic moment to Bohr magneton ratio 4.669 754 568(12) × 10−42.6 × 10−9
μd/μNDeuteron magnetic moment to nuclear magneton ratio 0.857 438 2335(22)2.6 × 10−9
mdDeuteron mass 3.343 583 7768(10) × 10−27kg3.0 × 10−10
mdc2Deuteron mass energy equivalent 3.005 063 234 91(94) × 10−10J3.1 × 10−10
mdc2Deuteron mass energy equivalent in MeV 1875.612 945 00(58)MeV3.1 × 10−10
mdDeuteron mass in u 2.013 553 212 544(15)u7.4 × 10−12
M(d)Deuteron molar mass 2.013 553 214 66(63) × 10−3kg mol−13.1 × 10−10
Ar(d)Deuteron relative atomic mass 2.013 553 212 544(15)7.4 × 10−12
rdDeuteron rms charge radius 2.127 78(27) × 10−15m1.3 × 10−4
μd/μeDeuteron-electron magnetic moment ratio −4.664 345 550(12) × 10−42.6 × 10−9
md/meDeuteron-electron mass ratio 3670.482 967 655(63)1.7 × 10−11
μd/μnDeuteron-neutron magnetic moment ratio −0.448 206 52(11)2.5 × 10−7
μd/μpDeuteron-proton magnetic moment ratio 0.307 012 209 30(79)2.6 × 10−9
md/mpDeuteron-proton mass ratio 1.999 007 501 2699(84)4.2 × 10−12
−e/meElectron charge to mass quotient −1.758 820 008 38(55) × 1011C kg−13.1 × 10−10
geElectron g factor −2.002 319 304 360 92(36)1.8 × 10−13
γeElectron gyromagnetic ratio 1.760 859 627 84(55) × 1011s−1 T−13.1 × 10−10
γe/2πElectron gyromagnetic ratio in MHz/T 28 024.951 3861(87)MHz T−13.1 × 10−10
μeElectron magnetic moment −9.284 764 6917(29) × 10−24J T−13.1 × 10−10
aeElectron magnetic moment anomaly 1.159 652 180 46(18) × 10−31.6 × 10−10
μe/μBElectron magnetic moment to Bohr magneton ratio −1.001 159 652 180 46(18)1.8 × 10−13
μe/μNElectron magnetic moment to nuclear magneton ratio −1838.281 971 877(32)1.7 × 10−11
meElectron mass 9.109 383 7139(28) × 10−31kg3.1 × 10−10
mec2Electron mass energy equivalent 8.187 105 7880(26) × 10−14J3.2 × 10−10
mec2Electron mass energy equivalent in MeV 0.510 998 950 69(16)MeV3.1 × 10−10
meElectron mass in u 5.485 799 090 441(97) × 10−4u1.8 × 10−11
M(e)Electron molar mass 5.485 799 0962(17) × 10−7kg mol−13.1 × 10−10
Ar(e)Electron relative atomic mass 5.485 799 090 441(97) × 10−41.8 × 10−11
me/mαElectron to alpha particle mass ratio 1.370 933 554 733(32) × 10−42.3 × 10−11
μe/μh′Electron to shielded helion magnetic moment ratio 864.058 239 86(70)8.1 × 10−10
μe/μp′Electron to shielded proton magnetic moment ratio −658.227 5856(27)4.1 × 10−9
eVElectron volt 1.602 176 634 × 10−19Jexact
(1eV)Electron volt-atomic mass unit relationship 1.073 544 100 83(33) × 10−9u3.1 × 10−10
(1eV)Electron volt-hartree relationship 3.674 932 217 5665(40) × 10−2Eh1.1 × 10−12
(1eV)Electron volt-hertz relationship 2.417 989 242… × 1014Hzexact
(1eV)Electron volt-inverse meter relationship 8.065 543 937… × 105m−1exact
(1eV)Electron volt-joule relationship 1.602 176 634 × 10−19Jexact
(1eV)Electron volt-kelvin relationship 1.160 451 812… × 104Kexact
(1eV)Electron volt-kilogram relationship 1.782 661 921… × 10−36kgexact
μe/μdElectron-deuteron magnetic moment ratio −2143.923 4921(56)2.6 × 10−9
me/mdElectron-deuteron mass ratio 2.724 437 107 629(47) × 10−41.7 × 10−11
me/mhElectron-helion mass ratio 1.819 543 074 649(53) × 10−42.9 × 10−11
μe/μμElectron-muon magnetic moment ratio 206.766 9881(46)2.2 × 10−8
me/mμElectron-muon mass ratio 4.836 331 70(11) × 10−32.3 × 10−8
μe/μnElectron-neutron magnetic moment ratio 960.920 48(23)2.4 × 10−7
me/mnElectron-neutron mass ratio 5.438 673 4416(22) × 10−44.0 × 10−10
μe/μpElectron-proton magnetic moment ratio −658.210 687 89(19)2.9 × 10−10
me/mpElectron-proton mass ratio 5.446 170 214 889(94) × 10−41.7 × 10−11
me/mτElectron-tau mass ratio 2.875 85(19) × 10−46.6 × 10−5
me/mtElectron-triton mass ratio 1.819 200 062 327(68) × 10−43.7 × 10−11
eElementary charge 1.602 176 634 × 10−19Cexact
e/ℏElementary charge over h-bar 1.519 267 447… × 1015A J−1exact
FFaraday constant 96 485.332 12…C mol−1exact
GF/(ℏc)3Fermi coupling constant 1.166 3787(6) × 10−5GeV−25.1 × 10−7
αFine-structure constant 7.297 352 5643(11) × 10−31.5 × 10−10
c1First radiation constant 3.741 771 852… × 10−16W m2exact
c1LFirst radiation constant for spectral radiance 1.191 042 972… × 10−16W m2 sr−1exact
EhHartree energy 4.359 744 722 2060(48) × 10−18J1.1 × 10−12
EhHartree energy in eV 27.211 386 245 981(30)eV1.1 × 10−12
(1E_h)Hartree-atomic mass unit relationship 2.921 262 317 97(91) × 10−8u3.1 × 10−10
(1E_h)Hartree-electron volt relationship 27.211 386 245 981(30)eV1.1 × 10−12
(1E_h)Hartree-hertz relationship 6.579 683 920 4999(72) × 1015Hz1.1 × 10−12
(1E_h)Hartree-inverse meter relationship 2.194 746 313 6314(24) × 107m−11.1 × 10−12
(1E_h)Hartree-joule relationship 4.359 744 722 2060(48) × 10−18J1.1 × 10−12
(1E_h)Hartree-kelvin relationship 3.157 750 248 0398(34) × 105K1.1 × 10−12
(1E_h)Hartree-kilogram relationship 4.850 870 209 5419(53) × 10−35kg1.1 × 10−12
ghHelion g factor −4.255 250 6995(34)8.0 × 10−10
μhHelion magnetic moment −1.074 617 551 98(93) × 10−26J T−18.7 × 10−10
μh/μBHelion magnetic moment to Bohr magneton ratio −1.158 740 980 83(94) × 10−38.1 × 10−10
μh/μNHelion magnetic moment to nuclear magneton ratio −2.127 625 3498(17)8.0 × 10−10
mhHelion mass 5.006 412 7862(16) × 10−27kg3.2 × 10−10
mhc2Helion mass energy equivalent 4.499 539 4185(14) × 10−10J3.1 × 10−10
mhc2Helion mass energy equivalent in MeV 2808.391 611 12(88)MeV3.1 × 10−10
mhHelion mass in u 3.014 932 246 932(74)u2.5 × 10−11
M(h)Helion molar mass 3.014 932 250 10(94) × 10−3kg mol−13.1 × 10−10
Ar(h)Helion relative atomic mass 3.014 932 246 932(74)2.5 × 10−11
σh′Helion shielding shift 5.996 7029(23) × 10−53.8 × 10−7
mh/meHelion-electron mass ratio 5495.885 279 84(16)2.9 × 10−11
mh/mpHelion-proton mass ratio 2.993 152 671 552(70)2.3 × 10−11
(1Hz)Hertz-atomic mass unit relationship 4.439 821 6590(14) × 10−24u3.2 × 10−10
(1Hz)Hertz-electron volt relationship 4.135 667 696… × 10−15eVexact
(1Hz)Hertz-hartree relationship 1.519 829 846 0574(17) × 10−16Eh1.1 × 10−12
(1Hz)Hertz-inverse meter relationship 3.335 640 951… × 10−9m−1exact
(1Hz)Hertz-joule relationship 6.626 070 15 × 10−34Jexact
(1Hz)Hertz-kelvin relationship 4.799 243 073… × 10−11Kexact
(1Hz)Hertz-kilogram relationship 7.372 497 323… × 10−51kgexact
ΔνCsHyperfine transition frequency of Cs-133 9 192 631 770Hzexact
α−1Inverse fine-structure constant 137.035 999 177(21)1.5 × 10−10
(1m^{-1})Inverse meter-atomic mass unit relationship 1.331 025 048 24(41) × 10−15u3.1 × 10−10
(1m^{-1})Inverse meter-electron volt relationship 1.239 841 984… × 10−6eVexact
(1m^{-1})Inverse meter-hartree relationship 4.556 335 252 9132(50) × 10−8Eh1.1 × 10−12
(1m^{-1})Inverse meter-hertz relationship 299 792 458Hzexact
(1m^{-1})Inverse meter-joule relationship 1.986 445 857… × 10−25Jexact
(1m^{-1})Inverse meter-kelvin relationship 1.438 776 877… × 10−2Kexact
(1m^{-1})Inverse meter-kilogram relationship 2.210 219 094… × 10−42kgexact
G0−1Inverse of conductance quantum 12 906.403 72…Ωexact
KJJosephson constant 483 597.8484… × 109Hz V−1exact
(1J)Joule-atomic mass unit relationship 6.700 535 2471(21) × 109u3.1 × 10−10
(1J)Joule-electron volt relationship 6.241 509 074… × 1018eVexact
(1J)Joule-hartree relationship 2.293 712 278 3969(25) × 1017Eh1.1 × 10−12
(1J)Joule-hertz relationship 1.509 190 179… × 1033Hzexact
(1J)Joule-inverse meter relationship 5.034 116 567… × 1024m−1exact
(1J)Joule-kelvin relationship 7.242 970 516… × 1022Kexact
(1J)Joule-kilogram relationship 1.112 650 056… × 10−17kgexact
(1K)Kelvin-atomic mass unit relationship 9.251 087 2884(29) × 10−14u3.1 × 10−10
(1K)Kelvin-electron volt relationship 8.617 333 262… × 10−5eVexact
(1K)Kelvin-hartree relationship 3.166 811 563 4564(35) × 10−6Eh1.1 × 10−12
(1K)Kelvin-hertz relationship 2.083 661 912… × 1010Hzexact
(1K)Kelvin-inverse meter relationship 69.503 480 04…m−1exact
(1K)Kelvin-joule relationship 1.380 649 × 10−23Jexact
(1K)Kelvin-kilogram relationship 1.536 179 187… × 10−40kgexact
(1kg)Kilogram-atomic mass unit relationship 6.022 140 7537(19) × 1026u3.2 × 10−10
(1kg)Kilogram-electron volt relationship 5.609 588 603… × 1035eVexact
(1kg)Kilogram-hartree relationship 2.061 485 788 7415(22) × 1034Eh1.1 × 10−12
(1kg)Kilogram-hertz relationship 1.356 392 489… × 1050Hzexact
(1kg)Kilogram-inverse meter relationship 4.524 438 335… × 1041m−1exact
(1kg)Kilogram-joule relationship 8.987 551 787… × 1016Jexact
(1kg)Kilogram-kelvin relationship 6.509 657 260… × 1039Kexact
aLattice parameter of silicon 5.431 020 511(89) × 10−10m1.6 × 10−8
d220Lattice spacing of ideal Si (220) 1.920 155 716(32) × 10−10m1.7 × 10−8
n0Loschmidt constant (273.15 K, 100 kPa) 2.651 645 804… × 1025m−3exact
n0Loschmidt constant (273.15 K, 101.325 kPa) 2.686 780 111… × 1025m−3exact
KcdLuminous efficacy 683lm W−1exact
Φ0Magnetic flux quantum 2.067 833 848… × 10−15Wbexact
RMolar gas constant 8.314 462 618…J mol−1 K−1exact
MuMolar mass constant 1.000 000 001 05(31) × 10−3kg mol−13.1 × 10−10
M(12C)Molar mass of carbon-12 12.000 000 0126(37) × 10−3kg mol−13.1 × 10−10
NAhMolar Planck constant 3.990 312 712… × 10−10J Hz−1 mol−1exact
VmMolar volume of ideal gas (273.15 K, 100 kPa) 22.710 954 64… × 10−3m3 mol−1exact
VmMolar volume of ideal gas (273.15 K, 101.325 kPa) 22.413 969 54… × 10−3m3 mol−1exact
Vm(Si)Molar volume of silicon 1.205 883 199(60) × 10−5m3 mol−15.0 × 10−8
xu(Mo Kα1)Molybdenum x unit 1.002 099 52(53) × 10−13m5.3 × 10−7
λC,μMuon Compton wavelength 1.173 444 110(26) × 10−14m2.2 × 10−8
gμMuon g factor −2.002 331 841 23(82)4.1 × 10−10
μμMuon magnetic moment −4.490 448 30(10) × 10−26J T−12.2 × 10−8
aμMuon magnetic moment anomaly 1.165 920 62(41) × 10−33.5 × 10−7
μμ/μBMuon magnetic moment to Bohr magneton ratio −4.841 970 48(11) × 10−32.3 × 10−8
μμ/μNMuon magnetic moment to nuclear magneton ratio −8.890 597 04(20)2.2 × 10−8
mμMuon mass 1.883 531 627(42) × 10−28kg2.2 × 10−8
mμc2Muon mass energy equivalent 1.692 833 804(38) × 10−11J2.2 × 10−8
mμc2Muon mass energy equivalent in MeV 105.658 3755(23)MeV2.2 × 10−8
mμMuon mass in u 0.113 428 9257(25)u2.2 × 10−8
M(μ)Muon molar mass 1.134 289 258(25) × 10−4kg mol−12.2 × 10−8
mμ/meMuon-electron mass ratio 206.768 2827(46)2.2 × 10−8
mμ/mnMuon-neutron mass ratio 0.112 454 5168(25)2.2 × 10−8
μμ/μpMuon-proton magnetic moment ratio −3.183 345 146(71)2.2 × 10−8
mμ/mpMuon-proton mass ratio 0.112 609 5262(25)2.2 × 10−8
mμ/mτMuon-tau mass ratio 5.946 35(40) × 10−26.7 × 10−5
ℏNatural unit of action 1.054 571 817… × 10−34J sexact
ℏNatural unit of action in eV s 6.582 119 569… × 10−16eV sexact
mec2Natural unit of energy 8.187 105 7880(26) × 10−14J3.2 × 10−10
mec2Natural unit of energy in MeV 0.510 998 950 69(16)MeV3.1 × 10−10
λ¯CNatural unit of length 3.861 592 6744(12) × 10−13m3.1 × 10−10
meNatural unit of mass 9.109 383 7139(28) × 10−31kg3.1 × 10−10
mecNatural unit of momentum 2.730 924 534 46(85) × 10−22kg m s−13.1 × 10−10
mecNatural unit of momentum in MeV/c 0.510 998 950 69(16)MeV/c3.1 × 10−10
ℏ/mec2Natural unit of time 1.288 088 666 44(40) × 10−21s3.1 × 10−10
cNatural unit of velocity 299 792 458m s−1exact
λC,nNeutron Compton wavelength 1.319 590 903 82(67) × 10−15m5.1 × 10−10
gnNeutron g factor −3.826 085 52(90)2.4 × 10−7
γnNeutron gyromagnetic ratio 1.832 471 74(43) × 108s−1 T−12.3 × 10−7
γn/2πNeutron gyromagnetic ratio in MHz/T 29.164 6935(69)MHz T−12.4 × 10−7
μnNeutron magnetic moment −9.662 3653(23) × 10−27J T−12.4 × 10−7
μn/μBNeutron magnetic moment to Bohr magneton ratio −1.041 875 65(25) × 10−32.4 × 10−7
μn/μNNeutron magnetic moment to nuclear magneton ratio −1.913 042 76(45)2.4 × 10−7
mnNeutron mass 1.674 927 500 56(85) × 10−27kg5.1 × 10−10
mnc2Neutron mass energy equivalent 1.505 349 765 14(76) × 10−10J5.0 × 10−10
mnc2Neutron mass energy equivalent in MeV 939.565 421 94(48)MeV5.1 × 10−10
mnNeutron mass in u 1.008 664 916 06(40)u4.0 × 10−10
M(n)Neutron molar mass 1.008 664 917 12(51) × 10−3kg mol−15.1 × 10−10
Ar(n)Neutron relative atomic mass 1.008 664 916 06(40)4.0 × 10−10
μn/μp′Neutron to shielded proton magnetic moment ratio −0.684 996 94(16)2.3 × 10−7
μn/μeNeutron-electron magnetic moment ratio 1.040 668 84(24) × 10−32.3 × 10−7
mn/meNeutron-electron mass ratio 1838.683 662 00(74)4.0 × 10−10
mn/mμNeutron-muon mass ratio 8.892 484 08(20)2.2 × 10−8
μn/μpNeutron-proton magnetic moment ratio −0.684 979 35(16)2.3 × 10−7
mn−mpNeutron-proton mass difference 2.305 574 61(67) × 10−30kg2.9 × 10−7
(mn−mp)c2Neutron-proton mass difference energy equivalent 2.072 147 12(60) × 10−13J2.9 × 10−7
(mn−mp)c2Neutron-proton mass difference energy equivalent in MeV 1.293 332 51(38)MeV2.9 × 10−7
mn−mpNeutron-proton mass difference in u 1.388 449 48(40) × 10−3u2.9 × 10−7
mn/mpNeutron-proton mass ratio 1.001 378 419 46(40)4.0 × 10−10
mn/mτNeutron-tau mass ratio 0.528 779(36)6.8 × 10−5
GNewtonian constant of gravitation 6.674 30(15) × 10−11m3 kg−1 s−22.2 × 10−5
G/ℏcNewtonian constant of gravitation over h-bar c 6.708 83(15) × 10−39(GeV/c2)−22.2 × 10−5
μNNuclear magneton 5.050 783 7393(16) × 10−27J T−13.2 × 10−10
μNNuclear magneton in eV/T 3.152 451 254 17(98) × 10−8eV T−13.1 × 10−10
μN/hcNuclear magneton in inverse meter per tesla 2.542 623 410 09(79) × 10−2m−1 T−13.1 × 10−10
μN/kNuclear magneton in K/T 3.658 267 7706(11) × 10−4K T−13.0 × 10−10
μN/hNuclear magneton in MHz/T 7.622 593 2188(24)MHz T−13.1 × 10−10
hPlanck constant 6.626 070 15 × 10−34J Hz−1exact
hPlanck constant in eV/Hz 4.135 667 696… × 10−15eV Hz−1exact
lPPlanck length 1.616 255(18) × 10−35m1.1 × 10−5
mPPlanck mass 2.176 434(24) × 10−8kg1.1 × 10−5
mPc2Planck mass energy equivalent in GeV 1.220 890(14) × 1019GeV1.1 × 10−5
TPPlanck temperature 1.416 784(16) × 1032K1.1 × 10−5
tPPlanck time 5.391 247(60) × 10−44s1.1 × 10−5
e/mpProton charge to mass quotient 9.578 833 1430(30) × 107C kg−13.1 × 10−10
λC,pProton Compton wavelength 1.321 409 853 60(41) × 10−15m3.1 × 10−10
gpProton g factor 5.585 694 6893(16)2.9 × 10−10
γpProton gyromagnetic ratio 2.675 221 8708(11) × 108s−1 T−14.1 × 10−10
γp/2πProton gyromagnetic ratio in MHz/T 42.577 478 461(18)MHz T−14.2 × 10−10
μpProton magnetic moment 1.410 606 795 45(60) × 10−26J T−14.3 × 10−10
μp/μBProton magnetic moment to Bohr magneton ratio 1.521 032 202 30(45) × 10−33.0 × 10−10
μp/μNProton magnetic moment to nuclear magneton ratio 2.792 847 344 63(82)2.9 × 10−10
σp′Proton magnetic shielding correction 2.567 15(41) × 10−51.6 × 10−4
mpProton mass 1.672 621 925 95(52) × 10−27kg3.1 × 10−10
mpc2Proton mass energy equivalent 1.503 277 618 02(47) × 10−10J3.1 × 10−10
mpc2Proton mass energy equivalent in MeV 938.272 089 43(29)MeV3.1 × 10−10
mpProton mass in u 1.007 276 466 5789(83)u8.2 × 10−12
M(p)Proton molar mass 1.007 276 467 64(31) × 10−3kg mol−13.1 × 10−10
Ar(p)Proton relative atomic mass 1.007 276 466 5789(83)8.2 × 10−12
rpProton rms charge radius 8.4075(64) × 10−16m7.6 × 10−4
mp/meProton-electron mass ratio 1836.152 673 426(32)1.7 × 10−11
mp/mμProton-muon mass ratio 8.880 243 38(20)2.3 × 10−8
μp/μnProton-neutron magnetic moment ratio −1.459 898 02(34)2.3 × 10−7
mp/mnProton-neutron mass ratio 0.998 623 477 97(40)4.0 × 10−10
mp/mτProton-tau mass ratio 0.528 051(36)6.8 × 10−5
πℏ/meQuantum of circulation 3.636 947 5467(11) × 10−4m2 s−13.0 × 10−10
h/meQuantum of circulation times 2 7.273 895 0934(23) × 10−4m2 s−13.2 × 10−10
λ¯CReduced Compton wavelength 3.861 592 6744(12) × 10−13m3.1 × 10−10
λ¯C,μReduced muon Compton wavelength 1.867 594 306(42) × 10−15m2.2 × 10−8
λ¯C,nReduced neutron Compton wavelength 2.100 194 1520(11) × 10−16m5.2 × 10−10
ℏReduced Planck constant 1.054 571 817… × 10−34J sexact
ℏReduced Planck constant in eV s 6.582 119 569… × 10−16eV sexact
ℏcReduced Planck constant times c in MeV fm 197.326 9804…MeV fmexact
λ¯C,pReduced proton Compton wavelength 2.103 089 100 51(66) × 10−16m3.1 × 10−10
λ¯C,τReduced tau Compton wavelength 1.110 538(75) × 10−16m6.8 × 10−5
R∞Rydberg constant 10 973 731.568 157(12)m−11.1 × 10−12
R∞cRydberg constant times c in Hz 3.289 841 960 2500(36) × 1015Hz1.1 × 10−12
R∞hcRydberg constant times hc in eV 13.605 693 122 990(15)eV1.1 × 10−12
R∞hcRydberg constant times hc in J 2.179 872 361 1030(24) × 10−18J1.1 × 10−12
S0/RSackur-Tetrode constant (1 K, 100 kPa) −1.151 707 534 96(47)4.1 × 10−10
S0/RSackur-Tetrode constant (1 K, 101.325 kPa) −1.164 870 521 49(47)4.0 × 10−10
c2Second radiation constant 1.438 776 877… × 10−2m Kexact
γh′Shielded helion gyromagnetic ratio 2.037 894 6078(18) × 108s−1 T−18.8 × 10−10
γh′/2πShielded helion gyromagnetic ratio in MHz/T 32.434 100 033(28)MHz T−18.6 × 10−10
μh′Shielded helion magnetic moment −1.074 553 110 35(93) × 10−26J T−18.7 × 10−10
μh′/μBShielded helion magnetic moment to Bohr magneton ratio −1.158 671 494 57(94) × 10−38.1 × 10−10
μh′/μNShielded helion magnetic moment to nuclear magneton ratio −2.127 497 7624(17)8.0 × 10−10
μh′/μpShielded helion to proton magnetic moment ratio −0.761 766 577 21(66)8.7 × 10−10
μh′/μp′Shielded helion to shielded proton magnetic moment ratio −0.761 786 1334(31)4.1 × 10−9
γp′Shielded proton gyromagnetic ratio 2.675 153 194(11) × 108s−1 T−14.1 × 10−9
γp′/2πShielded proton gyromagnetic ratio in MHz/T 42.576 385 43(17)MHz T−14.0 × 10−9
μp′Shielded proton magnetic moment 1.410 570 5830(58) × 10−26J T−14.1 × 10−9
μp′/μBShielded proton magnetic moment to Bohr magneton ratio 1.520 993 1551(62) × 10−34.1 × 10−9
μp′/μNShielded proton magnetic moment to nuclear magneton ratio 2.792 775 648(11)3.9 × 10−9
σdpShielding difference of d and p in HD 1.987 70(10) × 10−85.0 × 10−5
σtpShielding difference of t and p in HT 2.394 50(20) × 10−88.4 × 10−5
cSpeed of light in vacuum 299 792 458m s−1exact
gnStandard acceleration of gravity 9.806 65m s−2exact
atmStandard atmosphere 101 325Paexact
p∘Standard-state pressure 100 000Paexact
σStefan-Boltzmann constant 5.670 374 419… × 10−8W m−2 K−4exact
λC,τTau Compton wavelength 6.977 71(47) × 10−16m6.7 × 10−5
mτc2Tau energy equivalent 1776.86(12)MeV6.8 × 10−5
mτTau mass 3.167 54(21) × 10−27kg6.6 × 10−5
mτc2Tau mass energy equivalent 2.846 84(19) × 10−10J6.7 × 10−5
mτTau mass in u 1.907 54(13)u6.8 × 10−5
M(τ)Tau molar mass 1.907 54(13) × 10−3kg mol−16.8 × 10−5
mτ/meTau-electron mass ratio 3477.23(23)6.6 × 10−5
mτ/mμTau-muon mass ratio 16.8170(11)6.5 × 10−5
mτ/mnTau-neutron mass ratio 1.891 15(13)6.9 × 10−5
mτ/mpTau-proton mass ratio 1.893 76(13)6.9 × 10−5
σeThomson cross section 6.652 458 7051(62) × 10−29m29.3 × 10−10
gtTriton g factor 5.957 924 930(12)2.0 × 10−9
μtTriton magnetic moment 1.504 609 5178(30) × 10−26J T−12.0 × 10−9
μt/μBTriton magnetic moment to Bohr magneton ratio 1.622 393 6648(32) × 10−32.0 × 10−9
μt/μNTriton magnetic moment to nuclear magneton ratio 2.978 962 4650(59)2.0 × 10−9
mtTriton mass 5.007 356 7512(16) × 10−27kg3.2 × 10−10
mtc2Triton mass energy equivalent 4.500 387 8119(14) × 10−10J3.1 × 10−10
mtc2Triton mass energy equivalent in MeV 2808.921 136 68(88)MeV3.1 × 10−10
mtTriton mass in u 3.015 500 715 97(10)u3.3 × 10−11
M(t)Triton molar mass 3.015 500 719 13(94) × 10−3kg mol−13.1 × 10−10
Ar(t)Triton relative atomic mass 3.015 500 715 97(10)3.3 × 10−11
μt/μpTriton to proton magnetic moment ratio 1.066 639 9189(21)2.0 × 10−9
mt/meTriton-electron mass ratio 5496.921 535 51(21)3.8 × 10−11
mt/mpTriton-proton mass ratio 2.993 717 034 03(10)3.3 × 10−11
uUnified atomic mass unit 1.660 539 068 92(52) × 10−27kg3.1 × 10−10
ε0Vacuum electric permittivity 8.854 187 8188(14) × 10−12F m−11.6 × 10−10
μ0Vacuum magnetic permeability 1.256 637 061 27(20) × 10−6N A−21.6 × 10−10
RKVon Klitzing constant 25 812.807 45…Ωexact
mW/mZW to Z mass ratio 0.881 45(13)1.5 × 10−4
sin2θWWeak mixing angle 0.223 05(23)1.0 × 10−3
b′Wien frequency displacement law constant 5.878 925 757… × 1010Hz K−1exact
bWien wavelength displacement law constant 2.897 771 955… × 10−3m Kexact