⚗️ Mole Fraction Calculator
Enter the mass and molar mass of two components in a mixture to find each one’s mole fraction.
g
g/mol
g
g/mol
What This Calculator Does
The mole fraction is a way of expressing the concentration of a component in a mixture as the ratio of its moles to the total moles of all components present. Unlike molarity or molality, it is a dimensionless number between 0 and 1, and the mole fractions of all components in a mixture always add up to 1.
The Formula
For a two-component mixture, moles of each component are first found from moles = mass ÷ molar mass. The mole fraction of component A is then xA = moles of A ÷ (moles of A + moles of B), and similarly for component B. Because the two fractions always sum to 1, finding one automatically gives you the other.
A Few Notes
- Mole fraction is widely used in chemistry to describe gas mixtures (via partial pressures), vapor-liquid equilibrium, and colligative properties like vapor pressure lowering (Raoult’s Law).
- This calculator handles a two-component mixture; for mixtures with more components, the same approach extends by adding each component’s moles to the total.
- This tool is intended for general chemistry education and reference purposes.
Last reviewed August 2026