| Name | Symbol | Number | Exp | CGS Units | Relative Error (ppm) |
|---|---|---|---|---|---|
| speed of light in a vacuum | c | 2.99792458 | 10 | cm s-1 | exact |
| Planck constant | h | 6.6260755(40) | -27 | erg s | 0.60 |
| hbar | 1.05457266(63) | -27 | erg s | 0.60 | |
| Gravitational constant | G | 6.67259(85) | -8 | cm3 g-1 s-2 | 128 |
| Electron charge | e | 4.8032068(14) | -10 | esu | 0.30 |
| Mass of electron | me | 9.1093897(54) | -28 | g | 0.59 |
| Mass of proton | mp | 1.6726231(10) | -24 | g | 0.59 |
| Mass of neutron | mn | 1.6749286(10) | -24 | g | 0.59 |
| Mass of hydrogen | mH | 1.6733 | -24 | g | -- |
| Atomic mass unit | amu | 1.6605402(10) | -24 | g | 0.59 |
| Avagadro's number | NA | 6.0221367(36) | 23 | 0.59 | |
| Boltzmann constant | k | 1.380658(12) | -16 | erg k-1 | 8.5 |
| Electron volt | eV | 1.6021772(50) | -12 | erg | ~0.60 |
| Radiation density constant | a | 7.5646 | -15 | erg cm-3 K-4 | -- |
| Stefan-Boltzmann constant | \sigma | 5.67051(19) | -5 | erg cm-2 K-4 s-1 | 34 |
| Fine structure constant | \alpha | 7.29735308(33) | -3 | 0.045 | |
| Rydberg constant | R\inf | 2.1798741(13) | -11 | erg | 0.60 |