Molar Mass Calculator

Molar mass is the mass of one mole of a substance, expressed in grams per mole. It is the sum of the standard atomic weight of every atom named in the formula, so water at H2O comes to 18.015 g/mol.

Numerically they match for a molecule. Molecular weight is a relative, dimensionless figure, whereas molar mass attaches the unit grams per mole. This tool reports the value with the g/mol unit.

It uses IUPAC standard atomic weights, such as H 1.008, C 12.011, O 15.999, Na 22.99 and Cl 35.45, covering all 118 elements. For elements with no stable isotope, the mass number of the most common isotope is used.

Wrap repeated groups in parentheses or brackets, for example Ca(OH)2, and separate a hydrate with a dot, for example CuSO4.5H2O. A period, an asterisk or a middle dot all work as the hydrate separator, and spaces are ignored.

Yes. A formula like K4[Fe(CN)6] parses correctly through both bracket levels and returns 368.345 g/mol, so coordination compounds and complex ions are handled.

Yes, and it has to be. CO is carbon monoxide at 28.01 g/mol, while Co is the element cobalt at 58.933 g/mol. Always capitalise the first letter of a symbol and lowercase the rest.

The parser rejects any symbol it does not recognise and shows an 'Unknown element symbol' message instead of a mass. It will also flag mismatched brackets or stray characters so you can fix the formula.

Standard atomic weights are revised over time and some are quoted as ranges, so tools built on different tables can disagree in the last decimal. Differences around the third decimal place are normal.

No. It computes the average molar mass from standard atomic weights, so it does not handle a specific isotope such as deuterium, and ionic charges written like SO4^2- are not part of the mass.