Muon mass = 1.883 531 627 × 10−28 kg
- Value
- 1.883 531 627 × 10−28
- Unit
- kg
- Uncertainty
- 0.000 000 042 × 10⁻²⁸
- Copy-ready
1.883531627e-28
Rest mass of the muon — the electron's heavier, unstable cousin, made in vast numbers when cosmic rays hit the upper atmosphere.
Used to compute reaction energies, decay kinematics and binding energies. The lines below give the same mass in kilograms, atomic mass units (u), as an energy (mc², in J and MeV) and per mole, plus its ratio to other particles — all from the same CODATA adjustment, so they agree with each other.
The same quantity, other ways NIST lists it
| Quantity (NIST name) | Value | Unit | Uncertainty |
|---|---|---|---|
| Muon-electron mass ratio | 206.768 2827 | (dimensionless) | 0.000 0046 |
| Muon mass energy equivalent | 1.692 833 804 × 10−11 | J | 0.000 000 038 × 10⁻¹¹ |
| Muon mass energy equivalent in MeV | 105.658 3755 | MeV | 0.000 0023 |
| Muon mass in u | 0.113 428 9257 | u | 0.000 000 0025 |
| Muon molar mass | 1.134 289 258 × 10−4 | kg·mol⁻¹ | 0.000 000 025 × 10⁻⁴ |
| Muon-neutron mass ratio | 0.112 454 5168 | (dimensionless) | 0.000 000 0025 |
| Muon-proton mass ratio | 0.112 609 5262 | (dimensionless) | 0.000 000 0025 |
| Muon-tau mass ratio | 5.946 35 × 10−2 | (dimensionless) | 0.000 40 × 10⁻² |
NIST, Fundamental Physical Constants — Complete Listing (2022 CODATA adjustment), retrieved 2026-07-26.