Molar Mass Calculator

Type a chemical formula like C6H12O6, Ca(OH)2 or CuSO4·5H2O to get its molar mass and composition.

Case matters: Co is cobalt, CO is carbon monoxide. Use a dot or * for hydrates.
Formulas are case-sensitive.
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Molar mass
Composition by mass
Atoms
Moles in your sample
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How to Calculate Molar Mass

Molar mass = Σ (number of atoms × atomic weight) in g/mol

Atoms inside parentheses are multiplied by the number after the parenthesis: Ca(OH)₂ has 1 Ca, 2 O and 2 H. For hydrates like CuSO₄·5H₂O, add the water: 159.6 + 5 × 18.02 = 249.7 g/mol.

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Atomic weights come from the PubChem periodic table (National Library of Medicine), which follows IUPAC standard atomic weights. Some elements’ weights vary slightly in nature, so the last digit can differ between sources.