Muon mass
Atomic & nuclearMeasured
= 1.883 531 627(42) × 10−28 kg
- Value
- 1.883 531 627 × 10−28 kg
- Standard uncertainty
- 4.2 × 10−36 kg
- Relative uncertainty
- 2.2 × 10−8 (22 parts per billion)
- Status
- Measured
- Symbol
- Source
- CODATA 2022 via NIST · NIST entry
Use in a calculation
# muon mass, CODATA 2022 (NIST)
muon_mass = 1.883531627e-28 # kg, standard uncertainty 4.2e-36
# SciPy: scipy.constants.physical_constants['muon mass']What it is
The rest mass of the muon, an unstable heavier cousin of the electron (about 207 times its mass) that lives about 2.2 microseconds, in kilograms.
In other units
| Unit | Value | |
|---|---|---|
| CGS (g) | 1.883 531 627 × 10−25 | |
| u dalton / atomic mass unit | 0.113 428 9257 | unit is itself measured |
| MeV/c² MeV / c² | 105.658 3755 | |
| GeV/c² GeV / c² | 0.105 658 3755 |
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 | 1.883 531 627(42) × 10−28 | 2.2 × 10−8 | +0.0 σ of 2018 |
| 2018 | 1.883 531 627(42) × 10−28 | 2.2 × 10−8 | +0.7 σ of 2014 |
| 2014 | 1.883 531 594(48) × 10−28 | 2.5 × 10−8 | +1.2 σ of 2010 |
| 2010 | 1.883 531 475(96) × 10−28 | 5.1 × 10−8 | +1.6 σ of 2006 |
| 2006 | 1.883 531 30(11) × 10−28 | 5.8 × 10−8 | −0.3 σ of 2002 |
| 2002 | 1.883 531 40(33) × 10−28 | 1.8 × 10−7 | +1.9 σ of 1998 |
| 1998 | 1.883 531 09(16) × 10−28 | 8.5 × 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).