- Symbol
- mu, u
- Value
- 1.660 539 068 92 × 10−27
- Unit
- kg
- Uncertainty
- 0.000 000 000 52 × 10⁻²⁷
- Copy-ready
1.66053906892e-27
One twelfth of the mass of a carbon-12 atom; energy equivalent 931.494 103 72(29) MeV.
NIST, Fundamental Physical Constants — Complete Listing (2022 CODATA adjustment), retrieved 2026-07-26.
Particle and atomic masses
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UsePhysics. "Atomic mass constant (unified atomic mass unit) — 1.660 539 068 92 × 10−27 kg." UsePhysics.com. https://usephysics.com/reference/atomic-mass-constant. Value from the 2022 CODATA adjustment (NIST). Accessed [date].