Percent Composition Calculator

Calculate the percentage by mass of each element in a chemical compound. Enter element symbols and their counts to get accurate percent composition calculations.

Percent Composition Calculator

About Percent Composition

What is Percent Composition?

Percent composition is the percentage by mass of each element in a compound. It's calculated by dividing the mass of each element by the total molecular weight and multiplying by 100.

Formula

% Element = (Mass of Element / Total Molecular Weight) × 100

How to Use

  1. Enter the chemical symbol for each element
  2. Specify the number of atoms of each element
  3. Click Calculate to get percent composition
  4. Results show percentage and mass contribution of each element

Common Examples

  • H₂O: H: 11.19%, O: 88.81%
  • CO₂: C: 27.29%, O: 72.71%
  • NaCl: Na: 39.34%, Cl: 60.66%
  • C₆H₁₂O₆: C: 40.00%, H: 6.71%, O: 53.29%

Applications

  • Chemical analysis and identification
  • Quality control in manufacturing
  • Environmental monitoring
  • Forensic analysis
  • Nutritional labeling

Important Notes

  • Percentages always sum to 100%
  • Results are based on molecular formula, not empirical formula
  • Isotopic variations are not considered
  • Useful for comparing compounds with similar formulas