Chemistry
Average Atomic Mass Calculator
Average Atomic Mass Calculator calculate abundance-weighted average atomic mass from isotope masses and percentage or fractional abundances.
Chemistry
Average Atomic Mass Calculator
Calculate abundance-weighted average atomic mass from isotope masses and percentage or fractional abundances.
Formula
Average atomic mass = sum(isotope mass x fractional abundance).
About the Average Atomic Mass Calculator
Calculate abundance-weighted average atomic mass from isotope masses and percentage or fractional abundances.
How the Average Atomic Mass Calculator Works
Each isotope line is parsed as mass and abundance, abundances are normalized when their total differs slightly from one or 100, and weighted contributions are summed.
Formula
Average atomic mass = sum(isotope mass x fractional abundance).
The calculation runs in your browser. Values are validated for required ranges, compatible units, and method-specific restrictions before results are displayed.
Required Inputs
- Isotopes: mass, abundance (required).
- Abundance format (required).
Results Reported
The result panel reports the final answer and the intermediate quantities needed to check the calculation:
- Average atomic mass (u)
- Entered abundance total
- Normalized isotope contributions
- Isotopes included
Average Atomic Mass Calculator Example
Select Example Data in the calculator to load this reproducible input set:
| Input | Example value |
|---|---|
| Isotopes: mass, abundance | 34.96885268, 75.78
36.96590260, 24.22 |
| Abundance format | percent |
How to Use the Calculator
- Confirm that the calculator title and formula match the quantity you need.
- Enter every required value using the unit shown with its field.
- Select Example Data to inspect a valid input set, or enter your own values and select Calculate.
- Review all reported values and the displayed formula before using the answer.
- Use Copy Result or Download CSV when you need a reusable record.
Accuracy and Limitations
Use isotope masses and abundances from the same sample or reference. Large abundance totals that do not represent fractions or percentages indicate incorrect input.
Keep units consistent, use measurements that represent the actual situation, retain full precision during the calculation, and round only the final answer. Professional decisions may require current official rules, field measurements, laboratory methods, or specialist review.
Frequently Asked Questions
What does the Average Atomic Mass Calculator calculate?
Calculate abundance-weighted average atomic mass from isotope masses and percentage or fractional abundances.
Which formula does the Average Atomic Mass Calculator use?
Average atomic mass = sum(isotope mass x fractional abundance). Each isotope line is parsed as mass and abundance, abundances are normalized when their total differs slightly from one or 100, and weighted contributions are summed.
What should I check before using the Average Atomic Mass Calculator result?
Use isotope masses and abundances from the same sample or reference. Large abundance totals that do not represent fractions or percentages indicate incorrect input.