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Average Atomic Mass Calculator
Weighted average of isotope masses — see exactly how each isotope contributes to the periodic-table value.
Calculator
Results update as you type. Every step of the working is shown below.
Examples:
Result
Enter values above — the answer appears here instantly, with full working.
Formula used
Aᵣ = Σ(mᵢ × wᵢ)
Every result substitutes your values into this relation step by step above.
Assumptions
- Abundances are natural (terrestrial) percentages summing to ≈100 %.
- Isotope masses are exact isotopic masses in u, not mass numbers.