Constants & Units · constant
Atomic mass constant
u = 1.660 539 068 92(52) × 10⁻²⁷ kg
- Unit
- kg
- Value
- 1.660 539 068 92(52) × 10⁻²⁷
- Exact
- no
- Note
- One twelfth of a carbon-12 atom — the unit every atomic mass on the periodic table is quoted in.
- Symbol
- u
- Category
- Atomic & nuclear
- Numeric
- 1.66053906892e-27
- Uncertainty
- ±3.1 × 10⁻¹⁰ relative
Open on the Constants & Units shelf — the interactive card, the filters, and everything alongside it.