Percent Composition Calculator

Percent Composition Calculator

Percent composition (mass percent of each element) shows what fraction of a compound's molar mass comes from each element. It is essential for combustion analysis, empirical formula work, and verifying chemical formulas.

$$\text{element mass \%} = \frac{\text{element mass in 1 mol}}{\text{molar mass of compound}} \times 100$$

For sulfuric acid, $\text{H}_2\text{SO}_4$, the molar mass is about 98.07 g/mol. Hydrogen contributes $2 \times 1.008 = 2.016$ g, sulfur 32.06 g, and oxygen $4 \times 15.999 = 63.996$ g. Oxygen is the largest share at about 65.25%.

Enter any valid chemical formula (parentheses and hydrates supported) to get element-by-element breakdown. Related tools: Molar Mass Calculator, Molecular Weight Calculator, and Mass Percent Calculator.