Molar mass calculator

A molar mass calculator determines the molar mass and elemental mass percentages of a chemical compound from its formula. Enter a formula such as H₂O or CaCO₃, and the calculator adds the atomic masses of all its chemical elements to find the total molar mass in grams per mole (g/mol). One mole contains 6.022 × 10²³ particles, so molar mass creates a practical bridge between individual atoms and the quantities of chemical substances that can be weighed in a laboratory.

The calculator also shows the mass percentage of each element—the share of the compound’s total mass contributed by that element. For example, water has a molar mass of approximately 18.015 g/mol. Although an H₂O molecule contains two hydrogen atoms and only one oxygen atom, hydrogen contributes about 11.19% of its mass, while oxygen contributes about 88.81%. This happens because oxygen atoms are much heavier than hydrogen atoms, revealing that the number of atoms and their contribution by mass are not the same thing.

Chemists and students use molar mass and percentage composition to prepare solutions, analyse compounds, solve reaction calculations and understand what chemical substances are made of. The Chemistry mobile app includes this molar mass calculator, detailed mass-percentage results and a useful table of chemical elements. Download the app, enter a chemical formula and uncover the hidden numerical structure inside the substances around you.