Mole Fraction Calculator

This calculator finds the mole fraction of each component in a mixture, a fundamental way of expressing composition in chemistry. The mole fraction of a component is the number of moles of that component divided by the total number of moles of all components in the mixture. It tells you what proportion of the molecules present are of each kind, and because it is a ratio of like quantities it has no units and all the mole fractions in a mixture always add up to exactly one. Mole fraction is the natural way to describe composition in many areas of chemistry and physics: it appears in Raoult's law and Dalton's law of partial pressures for gases and solutions, in colligative properties like boiling point elevation and freezing point depression, and throughout thermodynamics, where it is often preferred over mass-based measures because chemical behaviour depends on numbers of molecules. This tool computes it. You enter the number of moles of each component, for up to three components, and the calculator returns the mole fraction of each, along with the total number of moles. The results update as you type, and you can confirm that the fractions sum to one. Use it for chemistry homework, for solution and gas calculations, or whenever you need composition in terms of moles. To find the moles of a component from a mass, divide the mass by the molar mass first. A common task is finding the mole fraction of a solute in a solvent, such as salt dissolved in water, where the solvent usually has many more moles and so the larger mole fraction. Leave a component at zero if your mixture has fewer than three parts.

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Mole fraction = moles of component / total moles. All mole fractions sum to 1. Dimensionless. Convert a mass to moles by dividing by the molar mass first.