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Percent Composition Calculator

Mass percent of an element in a compound.

Compute the mass percent of an element in a compound from the element's contribution to the molar mass and the total molar mass.

Daniel Oh By Daniel Oh
Reviewed by Dr. Helena Ortiz
Published Last reviewed 1 min read

Inputs

g
g/mol

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

% composition = (mass of element in 1 mol / molar mass of compound) × 100

In depth

Compute the mass percent of an element in a compound from the element's contribution to the molar mass and the total molar mass.