Molar Mass Calculator
Type a chemical formula and get its molar mass instantly — brackets, nested groups, and water of crystallisation all handled.
Supports parentheses and hydrates (use a dot, e.g. CuSO4.5H2O). Calculated from standard atomic masses.
How molar mass is calculated
The molar mass of a compound is the sum of the standard atomic masses of every atom in its formula. The calculator parses the formula, multiplies each element by its count (respecting brackets and hydrate dots), and adds the results.
Hydrates and parentheses
Use a dot or period for the water of crystallisation, for example CuSO4.5H2O, and ordinary brackets for groups, for example Ca(OH)2 or Al2(SO4)3. The bound water is included in the total, which matters when you weigh the hydrated salt. Learn more in molar mass and molecular weight.
Helpful references
Some links below are affiliate links. As an Amazon Associate we earn from qualifying purchases, at no extra cost to you. See our affiliate disclosure.
Frequently asked questions
How does the molar mass calculator handle hydrates?
Write the water of crystallisation after a dot, such as CuSO4.5H2O. The calculator adds the mass of the bound water, giving 249.69 g/mol for copper sulfate pentahydrate.
Can it parse parentheses?
Yes. Subscripts outside brackets multiply everything inside, including nested groups, so Ca(OH)2 and Al2(SO4)3 are calculated correctly.
Which atomic masses are used?
Standard atomic weights for the elements, the same weighted-average values shown on the periodic table.