Percent Composition Calculator
Calculate an element’s percentage by mass in a compound.
Enter Values
Calculation Result
How It Works
% = (element mass / compound molar mass) × 100
Use consistent units or select the units you need.
How to use this calculator
What to enter
Enter or select the following as requested: Element contribution; Molar mass unit; Compound molar mass. Follow the units, valid ranges, examples, and options displayed beside each field.
What the result means
The scientific result follows the physical or chemical relationship named by the calculator using the quantities and units entered. Check unit consistency, significant figures, sign conventions, and assumptions such as ideal conditions, constant acceleration, or a specified reaction model.
When to use it
Use this to solve or check a science problem or make an initial estimate. Confirm the formula and assumptions for the experiment or real-world system; calculated values do not replace measurement or safety procedures.