Molar Mass Calculator (from chemical formula)
Convert
Type a chemical formula and get its molar mass in grams per mole, plus a breakdown of each element's atomic mass, count, mass contribution and percentage by mass. The parser understands parentheses and brackets — like Ca(OH)2 or Fe2(SO4)3 — and hydrate dots such as CuSO4·5H2O. Standard atomic weights for all 118 elements are built in. Pair it with the molarity tool, which takes the molar mass to work out solution concentrations. Everything runs locally in your browser — nothing is uploaded.
| Element | Atomic mass | Count | Mass | % mass |
|---|---|---|---|---|
| C | 12.011 | 6 | 72.066 | 40.00% |
| H | 1.008 | 12 | 12.096 | 6.71% |
| O | 15.999 | 6 | 95.994 | 53.28% |
How to use
- Type a chemical formula (e.g. C6H12O6, Ca(OH)2, CuSO4·5H2O).
- Read the molar mass in g/mol.
- Check the per-element table for atomic mass, count and percent composition.
Frequently asked questions
- How do I write the formula?
- Use standard element symbols with the right capitalisation (Na, not NA) followed by counts: H2O, NaCl, C6H12O6. Parentheses and brackets group atoms — Ca(OH)2 — and a middle dot or asterisk marks hydrates, e.g. CuSO4·5H2O or CuSO4*5H2O.
- Which atomic weights are used?
- The conventional standard atomic weights (IUPAC) for every element. For elements with no stable isotope, the mass of the most stable or common isotope is used, so those values are approximate.
- What is percent composition?
- For each element it is that element's total mass in the formula divided by the molar mass, times 100 — useful in stoichiometry and for checking empirical formulas.
- Is my input sent anywhere?
- No. The calculation runs entirely in your browser; nothing is uploaded.
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