Electron mass energy equivalent
Atomic & nuclearMeasured
= 8.187 105 7880(26) × 10−14 J
- Value
- 8.187 105 7880 × 10−14 J
- Standard uncertainty
- 2.6 × 10−23 J
- Relative uncertainty
- 3.2 × 10−10 (318 parts per trillion)
- Status
- Measured
- Symbol
- Source
- CODATA 2022 via NIST · NIST entry
Use in a calculation
# electron mass energy equivalent, CODATA 2022 (NIST)
electron_mass_energy_equivalent = 8.187105788e-14 # J, standard uncertainty 2.6e-23
# SciPy: scipy.constants.physical_constants['electron mass energy equivalent']What it is
The rest energy (mass × c²) of the electron, the lightest charged particle and the carrier of electric current in metals, in joules.
In other units
| Unit | Value | |
|---|---|---|
| CGS (cm2 g s−2) | 8.187 105 788 × 10−7 | |
| eV electronvolt | 510 998.950 69 | |
| keV kiloelectronvolt | 510.998 950 69 | |
| MeV megaelectronvolt | 0.510 998 950 69 | |
| Eₕ hartree | 18 778.865 07 | unit is itself measured |
| Ry rydberg | 37 557.730 14 | unit is itself measured |
Converted with ConstantID's unit table; digits are rounded to the precision of the value, and a long exact value is rounded only for display. The relative uncertainty is unchanged by conversion to an exactly defined unit.
How the value changed, 1998–2022
Each point is one CODATA adjustment, plotted as its difference from the 2022 value; the bars show one standard uncertainty (an arrowhead means the bar runs off the chart).
Relative uncertainty
| CODATA | Value (uncertainty) | Relative uncertainty | Change from previous |
|---|---|---|---|
| 2022 | 8.187 105 7880(26) × 10−14 | 3.2 × 10−10 | +4.4 σ of 2018 |
| 2018 | 8.187 105 7769(25) × 10−14 | 3.1 × 10−10 | +1.3 σ of 2014 |
| 2014 | 8.187 105 65(10) × 10−14 | 1.2 × 10−8 | +1.6 σ of 2010 |
| 2010 | 8.187 105 06(36) × 10−14 | 4.4 × 10−8 | +1.7 σ of 2006 |
| 2006 | 8.187 104 38(41) × 10−14 | 5.0 × 10−8 | −0.2 σ of 2002 |
| 2002 | 8.187 1047(14) × 10−14 | 1.7 × 10−7 | +0.9 σ of 1998 |
| 1998 | 8.187 104 14(64) × 10−14 | 7.8 × 10−8 |
“Change from previous” is the shift in the value divided by the standard uncertainty of the previous adjustment. Earlier values are converted into the current unit where NIST changed it (for example J s to J Hz⁻¹).