Type any chemical formula — H2O, C6H12O6, Ca(OH)2 — and get its molar mass plus the mass percentage of every element.
molar mass (g/mol)
How to use this tool
Use element symbols with counts, e.g. H2SO4, and parentheses for groups, e.g. Ca(OH)2.
The headline number is the mass of one mole of the substance, in grams per mole.
Each element’s share of the total mass is listed, largest first — useful for percent-composition homework.
Formulas such as CuSO4.5H2O are not supported; enter the anhydrous formula or expand the water separately.
Formula & worked example
Glucose, C6H12O6: 6×12.011 + 12×1.008 + 6×15.999 = 180.156 g/mol. Calcium hydroxide, Ca(OH)2: 40.078 + 2×(15.999 + 1.008) = 74.092 g/mol. Water, H2O: 18.015 g/mol.
Limitations — read this before you rely on it
Atomic weights are standard average weights (e.g. Cl 35.45), so results are average molar masses, not single-isotope masses. Hydrate dots (·5H2O) and charges are not parsed; unknown element symbols are refused with an explanation.
Frequently asked questions
The mass of one mole of a substance: the sum of the atomic weights of every atom in its formula, in grams per mole.
Put a group in brackets and follow it with its count: Ca(OH)2 means one calcium plus two OH groups. Nested parentheses work too.
Because natural chlorine is a mix of isotopes; 35.45 is the abundance-weighted average. For single-isotope masses use the average atomic mass calculator.
No — charges are ignored by design here; enter the neutral formula (SO4) for the mass of the group.
The common elements from hydrogen to lead, including Fe, Cu, Zn, Br, I, Ag, Au and Hg. Rare or synthetic elements are not in the table.