Neutron mass = 1.674 927 500 56 × 10−27 kg
- Symbol
- mn
- Value
- 1.674 927 500 56 × 10−27
- Unit
- kg
- Uncertainty
- 0.000 000 000 85 × 10⁻²⁷
- Copy-ready
1.67492750056e-27
Energy equivalent 939.565 421 94(48) MeV — heavier than the proton, which is why a free neutron decays.
NIST, Fundamental Physical Constants — Complete Listing (2022 CODATA adjustment), retrieved 2026-07-26.
Particle and atomic masses
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