Quantity

Symbol

Value

Units

Relative Uncertainty (ppm)

Speed of light in Vacuum

c

299 792 458

Ms^-1

 (exact)

Permeability of vacuum

µ₀

4π×10^-7

=12.566 370614 …

NA^-2

10^-7 NA^-2

(exact)

Permittivity of vacuum

ε₀

1/µ₀c²

=8.854 187 817 …

10^-12Fm^-1

(exact)

Newtonian constant of gravitation

G

6.672 59

10^-11m³kg^-1s^-2

128

Planck constant

h

6.626 0755

10^-34Js

0.60

h/2π

ħ

1.054 572 66

10^-34Js

0.60

Elementary charge

e

1.602 177 33

10^-19C

0.30

Magnetic flux quantum, h/2e

Ф₀

2.067 834 61

10^-15Wb

0.30

Electron mass

m_e

9.109 3897

10^-31kg

0.59

Proton mass

m_p

1.672 6231

10^-27kg

0.59

Proton-electron mass ratio

m_p/m_e

1836.152701

0.020

Fine-structure constant, µ₀ce²/2h

α

7.297 353 08

0.045

Inverse fine-structure constant

α^-1

137 035 9895

10^-3

0.045

Rydberg constant, m_ecα²/2h

R∞

10 973 731.534

m^-1

0.0012

Avogadro constant

N_AL

6.022 1367

10²³mol^-1

0.59

Faraday constant, N_Ae

F

96 485.309

C mol^-1

0.30

Molar gas constant

R

8.314 510

J mol^-1K^-1

8.40

Boltzmann constant, R/N_A

k

1.380 658

10^-23JK^-1

8.50

Stafan-Boltzmann constant, (π²/60)k⁴/ħ³c²

σ

5.670 51

10^-8Wm^-2K^-4

34

Non-SI units used with SI

     Electronvolt, (e/C)J = {e}J

     (Unified) atomic mass unit, 1u=m_u= 1/12m(¹²C)

eV

 u

1.602 17733

1.660 5402

10^-19J

10^-27kg

0.30

0.59