Empirical Formula Calculator

Enter the elements along with their percentages to find the empirical formula. (Instructions)


This program determines both empirical and molecular formulas. To calculate the empirical formula, enter the composition (e.g. C=40%, H=6.67%, O=53.3%) of the compound. Enter an optional molar mass to find the molecular formula.

  • Percentages can be entered as decimals or percentages (i.e. 50% can be entered as .50 or 50%.)
  • To determine the molecular formula, enter the appropriate value for the molar mass.
  • Use uppercase for the first character in the element and lowercase for the second character. Examples: Fe, Au, Co, Br, C, O, N, F.

How To Determine Empirical/Molecular Formulas

Read our article on how to determine empirical and molecular formulas.

You can also ask for help in our forums.