Molar mass calculator
Enter any chemical formula — IUPAC atomic weights (2021).
Element symbols are case-sensitive. Parentheses and brackets are supported.
Your molar mass appears here as you type.
Formula and how to use it
The molar mass (molecular weight) of a compound is the sum of the atomic weights of every atom in its formula, expressed in g/mol. For glucose, C₆H₁₂O₆: (6 × 12.011) + (12 × 1.008) + (6 × 15.999) = 180.156 g/mol.
Atomic weights come from the IUPAC conventional table (2021); symbols are case-sensitive, so Co is cobalt while CO would be read as carbon and oxygen. Counts apply to the element or group they follow, including nested parentheses: in Ca(OH)₂ the (OH) group is doubled, giving one calcium, two oxygens, and two hydrogens.
This calculator parses any valid formula and shows both the total molar mass and the contribution of each element — useful for checking stoichiometry, converting between mass and moles, and preparing solutions. A curated compound library is pre-loaded for quick reference, and every entry links to its own page with the molar mass, conversions, and background notes.