Empirical & Molecular Formula Calculator

Quickly find the empirical and molecular formula of any compound from percent composition or elemental mass.

Options
Choose how you want to input element data
Display detailed calculation process
Display pie and bar charts
Enter to calculate molecular formula
Element Data
Examples & Help

Example Input Data Molar Mass Empirical Formula Molecular Formula
Glucose C: 40%, H: 6.7%, O: 53.3% 180 g/mol CH₂O C₆H₁₂O₆
Hydrogen Peroxide H: 5.05%, O: 94.95% 34 g/mol HO H₂O₂
Unknown C: 24g, H: 4g, O: 32g 180 g/mol CH₂O C₆H₁₂O₆

  1. Choose whether to input percent composition or element masses using the dropdown.
  2. Enter each element and its percent or mass in the input fields.
  3. (Optional) Enter the compound's molar mass to calculate the molecular formula.
  4. Click "Calculate" to get the empirical and molecular formulas.
  5. View step-by-step calculations and visual breakdowns by enabling the options.

Empirical Formula: The simplest ratio of atoms in a compound. It does not show the actual number of atoms—just the ratio.

Molecular Formula: Shows the exact number of atoms of each element in a compound. It is a multiple of the empirical formula, derived using the molar mass.