Percent composition calculator
Type a formula to see how much of it, by mass, each element makes up, such as carbon in glucose or nitrogen in a fertilizer.
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How to use it
- Enter chemical formula.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Element mass % = (atom count × atomic weight) ÷ molar mass of the compound × 100.
Example
Inputs: Chemical formula = C6H12O6. Result: Mass percent by element: C 40.00%, H 6.71%, O 53.28%; Molar mass: 180.156 g/mol.
Limits and caveats
- Shown percentages are rounded to 2 decimals, so they may not add up to exactly 100.00.
- Based on standard atomic weights, not on analysis of a real sample.
Questions about this tool
What percent of glucose is carbon?
About 40.00% by mass, since 6 carbons weigh 72.066 of its 180.156 g/mol.
What is the nitrogen content of urea, CH4N2O?
About 46.65%, which is why urea is one of the richest nitrogen fertilizers.
In what order are elements listed?
Hill order: carbon, then hydrogen, then the rest alphabetically; fully alphabetical when there is no carbon.