MasterTool

Mole Fraction Calculator

Calculate mole fraction instantly in your browser — the published formula, worked locally with no data sent anywhere.

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What this tool does

Calculate mole fraction instantly in your browser — the published formula, worked locally with no data sent anywhere. Mole fraction is dimensionless and temperature-independent. For gases it equals the volume fraction and the partial-pressure fraction (Dalton's law), which is why air is 0.78 N₂ / 0.21 O₂ by mole fraction.

How to use the Mole Fraction Calculator

  1. Enter or select moles of each component (comma or whitespace separated).
  2. Read the calculated result; change any measurement to compare alternatives.

Formula

mole fraction of a component Xᵢ = nᵢ ÷ Σn — its share of the total moles. All components' mole fractions sum to exactly 1.
amounts
Moles of each component (comma or whitespace separated)

Mole fraction is dimensionless and temperature-independent. For gases it equals the volume fraction and the partial-pressure fraction (Dalton's law), which is why air is 0.78 N₂ / 0.21 O₂ by mole fraction.

Worked example

For mole fraction calculator, the following measurements illustrate the exact method: Moles of each component (comma or whitespace separated): 1, 3.

Inputs

  • Moles of each component (comma or whitespace separated)1, 3

Result

  • Mole fraction of component 10.25
  • Total moles4
  • Component 1 (mol %)25
  • Component 2 (mol %)75

Results explained

Mole fraction of component 1
Mole fraction of component 1 from the formula above. Mole fraction is dimensionless and temperature-independent. For gases it equals the volume fraction and the partial-pressure fraction (Dalton's law), which is why air is 0.78 N₂ / 0.21 O₂ by mole fraction.
Total moles
Total moles from the formula above. Mole fraction is dimensionless and temperature-independent. For gases it equals the volume fraction and the partial-pressure fraction (Dalton's law), which is why air is 0.78 N₂ / 0.21 O₂ by mole fraction.
Component 1 (mol %)
Component 1 (mol %) from the formula above. Mole fraction is dimensionless and temperature-independent. For gases it equals the volume fraction and the partial-pressure fraction (Dalton's law), which is why air is 0.78 N₂ / 0.21 O₂ by mole fraction.
Component 2 (mol %)
Component 2 (mol %) from the formula above. Mole fraction is dimensionless and temperature-independent. For gases it equals the volume fraction and the partial-pressure fraction (Dalton's law), which is why air is 0.78 N₂ / 0.21 O₂ by mole fraction.

Frequently asked questions

mole fraction of a component Xᵢ = nᵢ ÷ Σn — its share of the total moles. All components' mole fractions sum to exactly 1.

Mole fraction is dimensionless and temperature-independent. For gases it equals the volume fraction and the partial-pressure fraction (Dalton's law), which is why air is 0.78 N₂ / 0.21 O₂ by mole fraction.

Every field is labelled with its unit — enter values in exactly the labelled unit and read the result in the labelled output unit. Fields with a unit symbol also support the site-wide imperial/metric switch, which converts before the formula runs.

It uses double-precision arithmetic and the published constants and formulas named on this page. The last displayed digit may be rounded, and real conditions can differ from the idealized model described in the assumptions.

Yes. Every calculation runs entirely in your browser; nothing you enter is uploaded, stored or shared.