Donaldson R F Molar Mass Calculator
Type a chemical formula such as C6H12O6, Ca(OH)2 or CuSO4.5H2O and get its molar mass, the mass of each element and the percentage composition.
How molar mass is calculated
The molar mass is the sum of the atomic masses of every atom in the formula, in grams per mole. For water, H2O: 2 × 1.008 + 15.999 = 18.015 g/mol. Brackets multiply everything inside them (Ca(OH)2 has 2 O and 2 H), and a dot separates the water of crystallisation in a hydrate (CuSO4.5H2O = CuSO4 + 5 H2O). Element symbols are case-sensitive: Co is cobalt but CO is carbon monoxide.
Atomic masses are the standard (conventional) atomic weights, rounded to at most 5 significant figures, so results agree with textbook tables to that precision. For elements with no stable isotope the mass number of the longest-lived isotope is used. The Avogadro constant used is 6.02214076 × 1023 per mole.