The reduced Planck constant ħ in eV·s and other units
ħ = h/2π is exact but irrational, so it has no final digit. Particle physicists most often need ħ in eV·s and the product ħc in MeV·fm, both below.
= 1.054 571 817… × 10−34 J s about this constant →
| Unit | Value | |
|---|---|---|
| eV·s electronvolt seconds | 6.582 119 569 51 × 10−16 | exact |
| MeV·s megaelectronvolt seconds | 6.582 119 569 51 × 10−22 | exact |
| erg·s erg seconds | 1.054 571 817 65 × 10−27 | exact |
| J·s joule seconds | 1.054 571 817 65 × 10−34 | exact |
How it is computed: h ÷ 2π ÷ e = 6.582 119 569 51 × 10−16.
ħc, the conversion particle physicists use
| ħc in MeV·fm | 197.326 980 459 |
| ħc in eV·nm | 197.326 980 459 |
| ħc in GeV·fm | 0.197 326 980 459 |
| ħc in eV·Å | 1973.269 804 59 |
| hc in eV·nm | 1239.841 984 33 |
All values computed from the CODATA 2022 value and unit definitions (SI Brochure, NIST SP 811). Exact values are rounded only for display. Checks.
Other conversions
- Speed of light in mph, km/h and other units
- Gravitational constant G in CGS and other units
- Planck constant in eV·s and other units
- Boltzmann constant in eV/K and other units
- Gas constant R in L·atm/(mol·K), cal/(mol·K) and other units
- Electron mass in MeV/c², grams and daltons
- Elementary charge in statcoulombs (esu) and other units
- Standard gravity in ft/s², m/s² and other units
- Avogadro constant per pound-mole and other units