Lists the defining constants of the SI.
| Constant | Symbol | Numerical value | SI Unit | Last Update | PID (Constant) |
|---|---|---|---|---|---|
| Avogadro constant | ${N_{\rm{A}}}$ | 6.022 140 76 x 10²³ | $$\text{mol}^{-1}\ \ $$ | 2019-05-20 |
|
| Boltzmann constant | ${k}$ | 1.380 649 x 10⁻²³ | $$\text{J}^{}\ \ \text{K}^{-1}\ \ $$ | 2019-05-20 |
|
| Planck constant | ${h}$ | 6.626 070 15 x 10⁻³⁴ | $$\text{J}^{}\ \ \text{s}^{}\ \ $$ | 2019-05-20 |
|
| elementary charge | ${e}$ | 1.602 176 634 x 10⁻¹⁹ | $$\text{C}^{}$$ | 2019-05-20 |
|
| hyperfine transition frequency of Cs-133 | $\Delta\nu_{\rm{Cs}}$ | 9 192 631 770 | $$\text{Hz}^{}$$ | 1967-10-13 |
|
| luminous efficacy | ${K_{\rm{cd}}}$ | 683 | $$\text{lm}^{}\ \ \text{W}^{-1}\ \ $$ | 1979-10-11 |
|
| speed of light | $c$ | 299 792 458 | $$\text{m}^{}\ \ \text{s}^{-1}\ \ $$ | 1975-06-03 |
|
