About the Molar Mass Calculator
What is the Molar Mass Calculator?
This molar mass calculator reads a chemical formula, counts every atom and adds up their standard atomic weights. It understands brackets, square brackets and water of crystallisation.
The table shows each element's contribution and its percentage by mass.
How to use the Molar Mass Calculator
- Chemical Formula (sample: CuSO4·5H2O)
- Press Calculate Molar Mass (results also refresh as you type). The result card shows the Molar Mass, along with Formula, Atoms per formula unit and Mass of one molecule.
Formula used
Molar mass = Σ (Number of atoms × Atomic weight)
- Atomic weights = IUPAC standard values (H 1.008, C 12.011, O 15.999, S 32.06)
- Mass % = element mass ÷ molar mass × 100
Element symbols are case-sensitive: Co is cobalt, CO is carbon monoxide.
Worked example
These are the sample values already filled in the calculator above, and the result it returns for them:
| Input | Sample value |
|---|---|
| Chemical Formula | CuSO4·5H2O |
| Result | Value |
|---|---|
| Molar Mass | 249.677 g/mol |
| Formula | CuSO₄·5H₂O |
| Atoms per formula unit | 21 |
| Mass of one molecule | 4.146 × 10⁻²² g |
Tips for using the Molar Mass Calculator
- Write hydrates with a dot, e.g. CuSO4·5H2O or CuSO4.5H2O.
- Molar mass in g/mol equals molecular mass in atomic mass units.