This template provides easy inclusion of the latest CODATA recommended values of physical constants in articles. It gives the most recent values published, and will be updated when newer values become available, which is typically every four years.
The values have been updated to the CODATA 2018 values. This includes the 2019 redefinition of SI base units, which made the values of several constants exact (e.g. e), whereas some previously exactly defined constants acquired an uncertainty (e.g. μ0).
symbol
yes
, the value is preceded by the symbol of the constant, followed by ≈ or = depending on whether or not round
is set.round
unit
no
, the unit of measurement is not shown.ref
no
, no reference is given. If set to only
, only the reference is given.after
runc
yes
, this will provide only the relative standard uncertainty of the value and its reference.Code | Constant | Value | Relative standard uncertainty |
---|---|---|---|
a0
|
Bohr radius | a0 = 5.29177210903(80)×10−11 m | ur(a0) = 1.5×10−10[1] |
alpha
|
fine-structure constant | α = 7.2973525693(11)×10−3 | ur(α) = 1.5×10−10[2] |
A90
|
conventional ampere | A90 = 1.00000008887... A | ur(A90) = 0[3] |
atm
|
standard atmosphere | atm = 101325 Pa | ur(atm) = 0[4] |
bwien
|
Wien wavelength displacement law constant | b = 2.897771955...×10−3 m⋅K | ur(b) = 0[5] |
bwien'
|
Wien frequency displacement law constant | b′ = 5.878925757...×1010 Hz⋅K−1 | ur(b′) = 0[6] |
c
|
speed of light | c = 299792458 m⋅s−1 | ur(c) = 0[7] |
c1
|
first radiation constant | c1 = 3.741771852...×10−16 W⋅m2 | ur(c1) = 0[8] |
c1L
|
first radiation constant for spectral radiance | c1L = 1.191042972...×10−16 W⋅m2⋅sr−1 | ur(c1L) = 0[9] |
c2
|
second radiation constant | c2 = 1.438776877...×10−2 m⋅K | ur(c2) = 0[10] |
C90
|
conventional coulomb | C90 = 1.00000008887... C | ur(C90) = 0[11] |
DnuCs
|
hyperfine structure transition frequency of caesium-133 | Δν(133Cs)hfs = 9192631770 Hz | ur(Δν(133Cs)hfs) = 0[12] |
e
|
elementary charge | e = 1.602176634×10−19 C | ur(e) = 0[13] |
Eh
|
Hartree energy | Eh = 4.3597447222071(85)×10−18 J | ur(Eh) = 1.9×10−12[14] |
Eh_eV
|
Hartree energy in eV | Eh = 27.211386245988(53) eV | ur(Eh) = 1.9×10−12[15] |
eps0
|
vacuum electric permittivity | ε0 = 8.8541878128(13)×10−12 F⋅m−1 | ur(ε0) = 1.5×10−10[16] |
eV
|
electronvolt | eV = 1.602176634×10−19 J | ur(eV) = 0[17] |
F
|
Faraday constant | F = 9.648533212...×104 C⋅mol−1 | ur(F) = 0[18] |
F90
|
conventional farad | F90 = 0.99999998220... F | ur(F90) = 0[19] |
G
|
Newtonian constant of gravitation | G = 6.67430(15)×10−11 m3⋅kg−1⋅s−2 | ur(G) = 2.2×10−5[20] |
G0
|
conductance quantum | G0 = 7.748091729...×10−5 S | ur(G0) = 0[21] |
g0
|
standard acceleration of gravity | g0 = 9.80665 m⋅s−2 | ur(g0) = 0[22] |
gammae
|
electron gyromagnetic ratio | γe = 1.76085963023(53)×1011 s−1⋅T−1 | ur(γe) = 3.0×10−10[23] |
gamman
|
neutron gyromagnetic ratio | γn = 1.83247171(43)×108 s−1⋅T−1 | ur(γn) = 2.4×10−7[24] |
gammap
|
proton gyromagnetic ratio | γp = 2.6752218744(11)×108 s−1⋅T−1 | ur(γp) = 4.2×10−10[25] |
ge
|
electron g-factor | ge− = −2.00231930436256(35) | ur(ge−) = 1.7×10−13[26] |
GF/hbarc3
|
Fermi coupling constant | GF/(ħc)3 = 1.1663787(6)×10−5 GeV−2 | ur(GF/(ħc)3) = 5.1×10−7[27] |
gmu
|
muon g-factor | gμ− = −2.0023318418(13) | ur(gμ−) = 6.3×10−10[28] |
gn
|
neutron g-factor | gn = −3.82608545(90) | ur(gn) = 2.4×10−7[29] |
gp
|
proton g-factor | gp = 5.5856946893(16) | ur(gp) = 2.9×10−10[30] |
h
|
Planck constant | h = 6.62607015×10−34 J⋅Hz−1 | ur(h) = 0[31] |
h_eV/Hz
|
Planck constant in eV/Hz | h = 4.135667696...×10−15 eV⋅Hz−1 | ur(h) = 0[32] |
H90
|
conventional henry | H90 = 1.00000001779... H | ur(H90) = 0[33] |
hbar
|
reduced Planck constant | ħ = 1.054571817...×10−34 J⋅s | ur(ħ) = 0[34] |
hbar_eVs
|
reduced Planck constant in eV⋅s | ħ = 6.582119569...×10−16 eV⋅s | ur(ħ) = 0[35] |
hcRinf
|
Rydberg unit of energy | hcR∞ = 2.1798723611035(42)×10−18 J | ur(hcR∞) = 1.9×10−12[36] |
h/2me
|
quantum of circulation | h/2me = 3.6369475516(11)×10−4 m2⋅s−1 | ur(h/2me) = 3.0×10−10[37] |
invalpha
|
inverse fine-structure constant | 1/α = 137.035999084(21) | ur(1/α) = 1.5×10−10[38] |
invG0
|
inverse conductance quantum | G0−1 = 12906.40372... Ω | ur(G0−1) = 0[39] |
k
|
Boltzmann constant | k = 1.380649×10−23 J⋅K−1 | ur(k) = 0[40] |
KJ
|
Josephson constant | KJ = 483597.8484...×109 Hz⋅V−1 | ur(KJ) = 0[41] |
KJ90
|
conventional value of Josephson constant | KJ-90 = 483597.9×109 Hz⋅V−1 | ur(KJ-90) = 0[42] |
lP
|
Planck length | lP = 1.616255(18)×10−35 m | ur(lP) = 1.1×10−5[43] |
malpha
|
alpha particle mass | mα = 6.6446573357(20)×10−27 kg | ur(mα) = 3.0×10−10[44] |
malphac2_GeV
|
alpha particle mass energy equivalent in GeV | mαc2 = 3.7273794066(11) GeV | ur(mαc2) = 3.0×10−10[45] |
md
|
deuteron mass | md = 3.3435837724(10)×10−27 kg | ur(md) = 3.0×10−10[46] |
md_Da
|
deuteron mass in daltons | md = 2.013553212745(40) Da | ur(md) = 2.0×10−11[47] |
me
|
electron mass | me = 9.1093837015(28)×10−31 kg | ur(me) = 3.0×10−10[48] |
me_Da
|
electron mass in daltons | me = 5.48579909065(16)×10−4 Da | ur(me) = 2.9×10−11[49] |
mec2_MeV
|
electron mass energy equivalent in MeV | mec2 = 0.51099895000(15) MeV | ur(mec2) = 3.0×10−10[50] |
mh
|
helion mass | mh = 5.0064127796(15)×10−27 kg | ur(mh) = 3.0×10−10[51] |
mh_Da
|
helion mass in daltons | mh = 3.014932247175(97) Da | ur(mh) = 3.2×10−11[52] |
mmu
|
muon mass | mμ = 1.883531627(42)×10−28 kg | ur(mμ) = 2.2×10−8[53] |
mmu/me
|
muon-to-electron mass ratio | mμ/me = 206.7682830(46) | ur(mμ/me) = 2.2×10−8[54] |
mn
|
neutron mass | mn = 1.67492749804(95)×10−27 kg | ur(mn) = 5.7×10−10[55] |
mn_Da
|
neutron mass in daltons | mn = 1.00866491595(49) Da | ur(mn) = 4.8×10−10[56] |
mnc2_MeV
|
neutron mass energy equivalent in MeV | mnc2 = 939.56542052(54) MeV | ur(mnc2) = 5.7×10−10[57] |
mP
|
Planck mass | mP = 2.176434(24)×10−8 kg | ur(mP) = 1.1×10−5[58] |
mp
|
proton mass | mp = 1.67262192369(51)×10−27 kg | ur(mp) = 3.1×10−10[59] |
mp_Da
|
proton mass in daltons | mp = 1.007276466621(53) Da | ur(mp) = 5.3×10−11[60] |
mp/me
|
proton-to-electron mass ratio | mp/me = 1836.15267343(11) | ur(mp/me) = 6.0×10−11[61] |
mpc2_MeV
|
proton mass energy equivalent in MeV | mpc2 = 938.27208816(29) MeV | ur(mpc2) = 3.1×10−10[62] |
mtau
|
tau mass | mτ = 3.16754(21)×10−27 kg | ur(mτ) = 6.8×10−5[63] |
MC12
|
molar mass of carbon-12 | M(12C) = 11.9999999958(36)×10−3 kg⋅mol−1 | ur(M(12C)) = 3.0×10−10[64] |
Mu
|
molar mass constant | Mu = 0.99999999965(30)×10−3 kg⋅mol−1 | ur(Mu) = 3.0×10−10[65] |
mu
|
atomic mass constant | mu = 1.66053906660(50)×10−27 kg | ur(mu) = 3.0×10−10[66] |
muc2
|
atomic mass constant energy equivalent | muc2 = 1.49241808560(45)×10−10 J | ur(muc2) = 3.0×10−10[67] |
muc2_MeV
|
atomic mass constant energy equivalent in MeV | muc2 = 931.49410242(28) MeV | ur(muc2) = 3.0×10−10[68] |
mu0
|
vacuum magnetic permeability | μ0 = 1.25663706212(19)×10−6 N⋅A−2 | ur(μ0) = 1.5×10−10[69] |
muB
|
Bohr magneton | μB = 9.2740100783(28)×10−24 J⋅T−1 | ur(μB) = 3.0×10−10[70] |
mue
|
electron magnetic moment | μe = −9.2847647043(28)×10−24 J⋅T−1 | ur(μe) = 3.0×10−10[71] |
mue/muB
|
electron magnetic moment to Bohr magneton ratio | μe/μB = −1.00115965218128(18) | ur(μe/μB) = 1.7×10−13[72] |
mumu
|
muon magnetic moment | μμ = −4.49044830(18)×10−26 J⋅T−1 | ur(μμ) = 2.2×10−8[73] |
muN
|
nuclear magneton | μN = 5.0507837461(15)×10−27 J⋅T−1 | ur(μN) = 3.1×10−10[74] |
mun
|
neutron magnetic moment | μn = −9.6623651(23)×10−27 J⋅T−1 | ur(μn) = 2.4×10−7[75] |
mun/muN
|
neutron magnetic moment to nuclear magneton ratio | μn/μN = −1.91304273(45) | ur(μn/μN) = 2.4×10−7[76] |
mup
|
proton magnetic moment | μp = 1.41060679736(60)×10−26 J⋅T−1 | ur(μp) = 4.2×10−10[77] |
mup/muB
|
proton magnetic moment to Bohr magneton ratio | μp/μB = 1.52103220230(46)×10−3 | ur(μp/μB) = 3.0×10−10[78] |
mup/muN
|
proton magnetic moment to nuclear magneton ratio | μp/μN = 2.79284734463(82) | ur(μp/μN) = 2.9×10−10[79] |
mW/mZ
|
W-to-Z mass ratio | mW/mZ = 0.88153(17) | ur(mW/mZ) = 1.9×10−4[80] |
NA
|
Avogadro constant | NA = 6.02214076×1023 mol−1 | ur(NA) = 0[81] |
NAh
|
molar Planck constant | NAh = 3.990312712...×10−10 J⋅Hz−1⋅mol−1 | ur(NAh) = 0[82] |
ohm90
|
conventional ohm | Ω90 = 1.00000001779... Ω | ur(Ω90) = 0[83] |
Phi0
|
magnetic flux quantum | Φ0 = 2.067833848...×10−15 Wb | ur(Φ0) = 0[84] |
R
|
molar gas constant | R = 8.314462618... J⋅mol−1⋅K−1 | ur(R) = 0[85] |
re
|
classical electron radius | re = 2.8179403262(13)×10−15 m | ur(re) = 4.5×10−10[86] |
Rinf
|
Rydberg constant | R∞ = 10973731.568160(21) m−1 | ur(R∞) = 1.9×10−12[87] |
RK
|
von Klitzing constant | RK = 25812.80745... Ω | ur(RK) = 0[88] |
RK90
|
conventional value of von Klitzing constant | RK-90 = 25812.807 Ω | ur(RK-90) = 0[89] |
rp
|
proton root-mean-square charge radius | rp = 0.8414(19) fm | ur(rp) = 2.2×10−3[90] |
sigma
|
Stefan–Boltzmann constant | σ = 5.670374419...×10−8 W⋅m−2⋅K−4 | ur(σ) = 0[91] |
sigmae
|
Thomson cross section | σe = 6.6524587321(60)×10−29 m2 | ur(σe) = 9.1×10−10[92] |
TP
|
Planck temperature | TP = 1.416784(16)×1032 K | ur(TP) = 1.1×10−5[93] |
tP
|
Planck time | tP = 5.391247(60)×10−44 s | ur(tP) = 1.1×10−5[94] |
V90
|
conventional volt | V90 = 1.00000010666... V | ur(V90) = 0[95] |
VmSi
|
molar volume of silicon | Vm(Si) = 1.205883199(60)×10−5 m3⋅mol−1 | ur(Vm(Si)) = 4.9×10−8[96] |
W90
|
conventional watt | W90 = 1.00000019553... W | ur(W90) = 0[97] |
Z0
|
characteristic impedance of vacuum | Z0 = 376.730313668(57) Ω | ur(Z0) = 1.5×10−10[98] |
((Physical constants|c|unit=no|after= [[metre per second|metres per second]].))
((Physical constants|mu0|symbol=yes))
((Physical constants|G|symbol=yes))
((Physical constants|hbar|round=2|symbol=yes))
The relative standard uncertainty of ''m''<sub>u</sub> is ((Physical constants|mu|runc=yes|after=.))
For the electron mass, ((Physical constants|me|runc=yes|symbol=yes|ref=no)).
NIST publishes the CODATA value of the [[elementary charge]].((Physical constants|e|ref=only))