Weighing a Molecule

A molecule's molecular weight is simply the sum of its atoms' weights — 12.011 for carbon, 1.008 for hydrogen, 15.999 for oxygen. This molecular weight calculator parses your formula and totals the mass in g/mol.

Beyond the Total

For each element the calculator reports its contribution and its percentage of the total mass. That mass-percentage view is exactly what empirical formulas, combustion analysis, and stoichiometry problems ask for — and it reveals which element dominates the molecule.

The Gram-Mole Link

Molecular weight is the exchange rate between the balance and the mole: grams ÷ g/mol = moles. Whether you are making a molar solution, balancing a reaction, or finding an empirical formula, everything starts with this single number.