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Percent Composition Calculator

Mass percent of each element, or of a solute in a solution.

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ⓘ Live results

Results
Percent composition
27.2921 %
Mass contributed
12.011 g
Remaining mass
31.998 g (72.7079%)

Working

  1. 1Mass of element = 12.011 × 1 = 12.011
  2. 2Percent = 12.011 ÷ 44.009 × 100 = 27.2921%

Quick answer

Percent composition is the mass of a component divided by the total mass of the compound, times 100: % = (mass of part / total mass) × 100.

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

How to use the Percent Composition Calculator

  1. 1Enter the atomic or molar mass of the element and how many atoms appear in the formula.
  2. 2Enter the molar mass of the whole compound.
  3. 3Read the mass percent.

Worked example

Using the values the calculator loads with:

Inputs

  • Mass of the element or solute12.011 g or g/mol
  • Number of atoms of that element1
  • Total mass of the compound44.009 g or g/mol

Results

  • Percent composition27.2921 %
  • Mass contributed12.011 g
  • Remaining mass31.998 g (72.7079%)
  1. Mass of element = 12.011 × 1 = 12.011
  2. Percent = 12.011 ÷ 44.009 × 100 = 27.2921%

Frequently asked questions

How do you find percent composition?

Divide the total mass of the element in one mole of the compound by the compound's molar mass, then multiply by 100.

What is the percent carbon in CO₂?

Carbon contributes 12.011 g/mol out of 44.009 g/mol, so CO₂ is 27.29% carbon by mass and 72.71% oxygen.

About this calculator

Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.