Percent Composition Calculator

Enter a compound formula to see its molar mass, atom counts, mass contribution, and percent composition by element.

Chemical formula

—Molar mass

How to use this Percent Composition Calculator

Calculate mass percent composition of each element in a chemical formula. Enter your values above and the result is calculated directly in your browser. No account is required.

Fast answer, clear inputs

This tool is built around one job: give the answer quickly without forcing a signup or hiding the result. Related tools are linked nearby when the next calculation or conversion is useful.