Molar Mass Calculator
H2O, C6H12O6, Fe2(SO4)3 — formula weight from a string. Click any i for detail.
Formula
Formula
i
Formula
Element symbols and optional parentheses. Example Ca(OH)2. |
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How to use this calculator
- Type a chemical formula using element symbols.
- Use parentheses for groups, like Ca(OH)2.
- Read molar mass in g/mol.
- Fix typos if an unknown symbol errors.
Results explained
Sums atomic weights × subscripts for a classroom element table. Hydrates with dot notation (CuSO4·5H2O) are not parsed; expand H and O counts manually.
Quick reference: formula weight
H2O ≈ 18.015 g/mol.
| Item | Detail |
|---|---|
| Water | H2O → ~18 g/mol |
| CO2 | C + 2O → ~44 g/mol |
| Parentheses | Ca(OH)2 doubles OH |
| Units | g/mol same as daltons numerically |
Missing elements error instead of guessing.
How the estimate is built
molar mass = Σ (atomic weight × atom count).
Example scenario
H2O → about 18.015 g/mol.
FAQ
How do I enter copper sulfate pentahydrate?
Write CuSO4 with five H2O worth of H and O added explicitly.
Are isotopes averaged?
Yes, standard atomic weights are averaged like periodic-table classroom values.
Is this osmolarity?
No. Osmolarity is a clinical serum formula page, not stoichiometry.