Atomic Mass Unit Converter
Convert atomic mass units into any other weight unit. One unit, also called a dalton, is one twelfth of the mass of a carbon-12 atom.
Convert atomic mass units
Frequently Asked Questions
One twelfth of the mass of an unbound carbon-12 atom at rest: 1.66053906892 × 10⁻²⁷ kg, the 2022 CODATA value.
Yes. The dalton (Da) and the unified atomic mass unit (u) are the same unit; dalton is preferred in biochemistry.
Because the numbers are tiny. A unit is about 1.7 × 10⁻²⁴ grams, which no fixed number of decimal places would show usefully.
The definition has not, but the measured value is refined periodically. This uses the 2022 CODATA figure.