| Constant Name |
Symbol |
Value |
Dimension |
Definition (Notes) |
| acceleration due to gravity |
g |
9.80665 |
m/s2 |
|
| atomic mass unit, unified |
u |
1.660538782(83) × 10-27 |
kg |
(Mass of 12C)/12 |
| astronomical unit |
au |
1.4959787066(30) × 1011 |
m |
Mean Earth to Sun distance |
| Avogadro constant |
R |
6.02214179(30) × 1023 |
mol-1 |
Particles in a mole of substance |
| Bohr magneton |
µB |
9.27400915(23) × 10-24 |
m2•A |
|
| Bohr radius |
aoo |
5.2917720859(36) × 10-11 |
m |
= α/(4πR∞) |
| Boltzmann constant |
k |
1.3806504(24) × 10-23 |
J/K |
|
| Charge/Quantum ratio |
|
2.417989454(60) × 1014 |
A/J |
= e/h |
| Conductance quantum |
G0 |
7.7480917004(53) × 10-5 |
S |
= 2e2/h |
| day, mean sidereal |
dsidereal |
86164.090530833 |
s |
23h + 56m +4.090 530833s |
| deuteron (2H) mass |
md |
3.34358320(17) × 10-27 |
Kg |
1875.612793(47) MeV/c2 = 2.013553212724(78) u |
| Earth mass |
ME |
5.9736(76) × 1024 |
Kg |
|
| Earth radius (equatorial) |
RE |
6.37814 × 106 |
m |
|
| electron charge magnitude |
eV |
1.602176487(40) × 10-19 |
C |
|
| electron rest mass |
me |
9.10938215(45) × 10-31 |
Kg |
0.510998910(13) MeV = 5.4857990942(23) × 10-4 u |
| electron radius, classical |
re |
2.8179402894(58) × 10-15 |
m |
= e2(4πε0mec2) |
| electron Compton wavelength |
λe |
2.4263102175(33) × 10-12 |
m |
= h/cme |
| fine structure constant |
α |
7.2973525376(50) × 10-3 |
N/A |
= μ0ce2/2h |
| gravitation constant |
G |
6.67428(67) × 10-11
| m3/(kg.s2) |
= GM1M2/r122 |
| Hubble constant |
H0 |
2.29(13) × 10-18 |
s-1 |
|
| Josephson constant |
KJ
| 4.83597891(12) × 10-14 |
Hz/V |
= 2e/h |
| light year (deprecated) |
ly |
9.4607304 × 1016 |
m |
|
| magnetic constant (vacuum permeability) |
µ0 |
2.067833667(52) × 10-15 |
W.b |
= h/2e |
| magnetic flux quantum |
Φ0 |
1.2566370614 × 10-6 |
N·A-2 |
= 4π × 10-7 N·A-2 |
| Naperian (natural) logarithm base |
e |
2.718281828459045235 |
|
|
| nuclear magneton |
µN |
5.05078324(13) × 10-27 |
Kg |
|
| parsec (au/arcsec) |
pc |
3.08568025 × 1016 |
m |
|
| permittivity of free space |
ε0 |
8.854187817 × 10-12 |
F/m |
|
| Planck constant |
h |
6.62606896(33) × 10-34 |
J.s |
|
| Planck constant, reduced (Angular) |
hbar |
1.054 571628(53) × 10-34 |
J.s |
|
| Planck length |
lp |
1.616252(81) × 10-35 |
m |
= ctp |
| Planck mass |
mp |
2.17644(11) × 10-8 |
kg |
= √(h/2π)c/G |
| Planck time |
tp |
5.39124(27) × 10-44 |
s |
= (h/2π)/mpc2 |
| Planck temperature |
|
1.416785(71) × 1032 |
K |
= mpc2/k |
| proton rest mass |
mp |
1.672621637(83) × 10-27 |
kg |
|
| Quantum of circulation |
|
3.6369475199(50) × 10-4 |
m2/s |
= h/2me |
| Rydberg energy |
R∞ |
1.0973731568527(73) × 107 |
m-1 |
= cα2me/2h |
| speed of light in vacuum |
c |
2.99792458 × 108 |
m/s |
|
| Stefan-Boltzmann constant |
σ |
5.6704(40) × 10-8 |
W/(m2 K4) |
= 2π5k4/15h3c2 |
| Thompson cross section |
σT |
6.6524 × 10-29 |
m2 |
= 8π.r02/3 |
| Wien displacement law constant |
b |
2.8977685(51) × 10-3 |
m.K |
|
| year, sidereal (fixed star to fixed star, 1994) |
ysidereal |
31558149.8 |
s |
|
| year, tropical (equinox to equinox, 1994) |
y |
31556925.2 |
s |
|
| Von Klitzing constant |
RK |
2.5812807557(18) × 104 |
Ω |
= h/e2 |
