Mole fraction calculator

Divide a component’s moles by the total moles to find its mole fraction.

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Moles of target component

Moles of all other components

Answer

…

Divide a component’s moles by the total moles to find its mole fraction.

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Precision and calculation record

Decimal places in numeric results and text downloads

Rounding changes displayed numbers, not the calculation. Text, fractions, matrices and CSV schedules keep their own formatting. Automatic keeps up to 12 significant digits, with money shown to cents where applicable.

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Save the current answer, then change an input to compare. This clears when you leave.

Formula and assumptions

The second input excludes the target component. Fractions sum to one when every component is included. Chemical reactions and dissociation can change the counted entities.

Automatic precision shows numbers to 12 significant digits. Thousands separators such as 1,000 are accepted; use a dot for decimals.

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Updated 2026-09-26

Using Mole fraction calculator

Divide a component’s moles by the total moles to find its mole fraction.

The second input excludes the target component. Fractions sum to one when every component is included. Chemical reactions and dissociation can change the counted entities.

Next: Molarity calculator

A worked example

Example inputs: moles of target component = 2, moles of all other components = 3. Mole fraction = 0.4.

Before you use the result

The second input excludes the target component. Fractions sum to one when every component is included. Chemical reactions and dissociation can change the counted entities.

Example results for moles of target component

These examples use Moles of all other components: 3. They are reference calculations, not recommended settings.

Moles of target component	Mole fraction
1	0.25
2	0.4
4	0.571428571429

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