Constants & Units · constant
Neutron mass
m_n = 1.674 927 500 56(85) × 10⁻²⁷ kg
- Unit
- kg
- Value
- 1.674 927 500 56(85) × 10⁻²⁷
- Exact
- no
- Note
- Heavier than the proton by 0.14% — which is why free neutrons decay in ~15 minutes.
- Symbol
- m_n
- Category
- Atomic & nuclear
- Numeric
- 1.67492750056e-27
- Uncertainty
- ±5.1 × 10⁻¹⁰ relative
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