Percent Composition Calculator

Find each supported element’s percentage of a compound’s calculated molar mass.

About the Percent Composition Calculator

Percent composition compares each element’s mass contribution with the formula’s total molar mass.

How to use it

  1. Enter a supported compound formula.
  2. Calculate its element counts and molar mass.
  3. Review the percentage by mass for every parsed element.

Formula

Element percent = element mass contribution ÷ compound molar mass × 100.

Example

For CaCO3, calcium, carbon and oxygen contributions are each divided by the total calculated molar mass.

Notes

Percentages use the calculator’s stored reference atomic weights and may differ slightly with other reference tables or rounding.