What is the Molar Mass Calculator?

Molar mass (molecular weight) is the mass of one mole of a substance, expressed in grams per mole (g/mol). Chemists use it to convert between grams and moles in stoichiometry, lab prep, and homework problems. This calculator parses a chemical formula — including parentheses and hydrates — looks up standard IUPAC atomic weights for each element, and returns the total molar mass plus an element-by-element breakdown. Enter H2O, NaCl, Ca(OH)2, or CuSO4·5H2O and get instant results in your browser with no signup.

How to use the Molar Mass Calculator

1. Type a chemical formula using element symbols and subscripts (e.g. H2O, C6H12O6).
2. Use parentheses for groups, e.g. Ca(OH)2 for calcium hydroxide.
3. For hydrates, separate with · or * (e.g. CuSO4·5H2O).
4. Read the molar mass in g/mol and review the per-element contribution table.
5. Copy the breakdown for your lab notebook or homework.

Common use cases

• Converting between grams and moles in stoichiometry homework
• Checking the molecular weight of a reagent before preparing a solution
• Verifying hydrate formulas such as copper(II) sulfate pentahydrate

Frequently asked questions

What is molar mass?

Molar mass is the mass of one mole of a chemical substance, usually given in g/mol. It equals the sum of atomic masses for all atoms in the formula unit.

How do I enter hydrates?

Use a middle dot or asterisk between the main compound and water of crystallization, e.g. CuSO4·5H2O or CuSO4*5H2O.

Which atomic weights are used?

The calculator uses standard IUPAC atomic weights for elements 1–118. Values are suitable for education and quick estimates.