BEST VALUES OF FUNDAMENTAL CONSTANTS
(1986)
Relative uncertainty
Quantity
Symbol
Value
Units
(parts per million)
speed of light in vacuum
c
299792458
ms-1
permeability of vacuum
0
4 x 10-7
NA-2
=12.566370614...
10-7 NA-2
(exact)
=8.854187817....
10-12 Fm-1
(exact)
G
6.67259(85)
10-11 m3 kg-1s-1
128
h
6.6260755(40)
10-34 Js
0.60
4.1356692(12)
10-15 eVs
0.30
1.05457266(63)
10-34 Js
0.60
6.5821220(20)
10-16 eVs
0.30
UNIVERSAL CONSTANTS
permittivity of vacuum
Newtonian constant
0
1 / 0c
(exact)
2
of gravitation
Planck constant
in electron volts
 =h/2
in electron volts
ELECTROMAGNETIC CONSTANTS
elementary charge
e
1.60217733(49)
10-19 C
0.30
magnetic flux quantum, h/2e
0
2.06783461(61)
10-15 Wb
0.30
4.8359767(14)
1014 HzV-1
0.30

0.045
Josephson frequency-voltage ratio 2e/h
2
-5
-1
quantized Hall conductance
e /h
3.87404614(17)
10
Bohr magneton, e  /2me
B
9.2740154(31)
10-24 JT-1
0.34
5.78838263(52)
10-5 eVT-1
0.089
5.0507866(17)
10-27 JT-1
0.34
3.15245166(28)
10-8 eVT-1
0.089

7.29735308(33)
10-3
0.045
 1
137.0359895(61)
R
10973731.534(13)
in electron volts
nuclear magneton, e  /2mp
N
in electron volts
ATOMIC CONSTANTS
fine-structure constant,
e 2 / 4 0 c
inverse fine-structure, constant
Rydberg constant,
1
me c 2 / h
2
47
0.045
m-1
0.0012
Relative uncertainty
Quantity
Bohr radius, 4 0  / me e
2
2
quantum of circulation
Symbol
Value
Units
(parts per million)
a0
0.529177249(24)
10-10 m
0.045
h/2me
3.63694807(33)
10-4 m2s-1
0.089
h/me
7.27389614(65)
10-4 m2s-1
0.089
me
9.1093897(54)
10-31 kg
0.59
5.48579903(13)
10-4 u
0.023
0.51099906(15)
MeV
0.30
Electron
electron mass
mec2 in electron volts
-4
electron-proton mass ratio
me/mp
5.44617013(11)
10
electron specific charge
-e/me
-1.75881962(53)
1011 Ckg-1
0.30
Compton wavelength, h/mec
c
2.42631058(22)
10-12 m
0.089
c
3.86159323(35)
10-13 m
0.089
re
2.81794092(38)
10-15 m
0.13
Thomson cross section, (8/3) re
e
0.66524616(18)
10-28 m2
0.27
electron magnetic moment
e
928.47701(31)
10-26 JT-1
0.34
in Bohr magnetons
e /  B
1.001159652193(10)
1 x 10-5
in nuclear magnetons
e /  N
1838.282000(37)
0.020
 e /  B 1
ae
1.159652193(10)
2(1  ae )
ge
2.002319304386(20)
m
1.8835327(11)
10-28 kg
0.61
0.113428913(17)
u
0.15
105.658389(34)
MeV
0.32
c / 2 a0
classical electron radius,
0.020
e 2 / 4 0 me c 2
2
electron magnetic moment
anomaly,
electron g-factor,
10-3
0.0086
1 x 10-5
Muon
muon mass
m c 2 in electron volts
muon-electron mass ratio
m  / me
206.768262(30)
muon magnetic moment

4.4904514(15)
10-26 JT-1
0.33
 / B
4.84 197097(71)
10-3
0.15
in Bohr magnetons,
48
0.15
Relative uncertainty
Quantity
Symbol
Value
Units
(parts per million)
a
1.1659230(84)
10-3
g
2.002331846(17)
mP
1.6726231(10)
10-27 kg
0.59
1.007276470(12)
u
0.012
938.27231(28)
MeV
0.30
muon magnetic moment anomaly



/( e / 2m  ) 1
muon g-factor, 2(1+a)
7.2
0.0084
Proton
proton mass
mpc2 in electron volts
proton-electron mass ratio
mp/me
1836.152701(37)
proton specific charge
e/mp
9.5788309(29)
107 Ckg-1
0.30
1.32141002(12)
10-15 m
0.089
1.41060761(47)
10-26 JT-1
0.34
proton Compton wavelength, h/mpc c,p
proton magnetic moment
p
0.020
in Bohr magnetons
p/B
1.521032202(15)
in nuclear magnetons
p/N
2.792847386(63)
mn
1.6749286(10)
10-27 kg
0.59
1.008664904(14)
u
0.014
939.56563(28)
MeV
0.30
10
-3
0.010
0.023
Neutron
neutron mass
2
mnc in electron volts
neutron-electron mass ratio
mn/me
1838.683662(40)
neutron-proton mass ratio
mn/mp
1.001378404(9)
neutron Compton wavelength, h/mnc c,n
0.022
0.009
-15
1.31959110(12)
10
n
0.96623707(40)
l0-26 JT-1
0.41
in Bohr magnetons
n/B
1.04187563(25)
10-3
0.24
in nuclear magnetons
n/N
1.91304275(45)
md
3.3435860(20)
10-27 kg
0.59
2.013553214(24)
u
0.012
1875.61339(57)
MeV
0.30
neutron magnetic moment
m
0.089
0.24
Deuteron
deuteron mass
mdc2 in electron volts
deuteron-electron.mass ratio
md/me
3670.483014(75)
0.020
deuteron-proton mass ratio
md/mp
1.999007496(6)
0.003
deuteron magnetic moment
d
0.43307375(15)
10-26 JT-1
0.34
in Bohr magnetons,
d/B
0.4669754479(91)
10-3
0.019
in nuclear magnetons,
d/N
0.857438230(24)
49
0.028
Relative uncertainty
Quantity
Symbol
Value
Units
(parts per million)
6.0221367(36)
1023 mol-1
0.59
1.6605402(10)
10-27 kg
0.59
931.49432(28)
MeV
0.30
PHYSICO-CHEMICAL CONSTANTS
Avogadro constant
NA
1 12
atomic mass constant, mu= m( C) mu
2
muc2 in electron volts
-1
Faraday constant
F
96485.309(29)
C mol
molar gas constant
R
8.314510(70)
J mol-1 K-1
8.4
Boltzmann constant, R/NA
k
1.380658(12)
10-23 JK-1
8.5
in electron volts
-3
0.30
-1
8.617385(73)
10 eVK
8.4
22.41410(19)
liter/mol
8.4
molar volume (ideal gas), RT/p
T = 273.15K, p = 101325Pa
Loschmidt constant, NA/Vm
Vm
25
-3
n0
2.686763(23)
10 m
8.5

5.67051(19)
10-8 Wm-2K-4
34
b
2.897756(24)
10-3 mK
8.4
Stefan-Boltzmann constant,
(2/60)k4/  3c2
Wien displacement law constant
50