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Mole Calculator

Calculate moles, mass, molar mass, or particle count.

Mole Calculator tool

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About This Tool

The mole connects measurable laboratory-scale quantities to the number of microscopic entities in a substance. This calculator handles two foundational relationships: n = m/M for mass, moles, and molar mass, and N = nNₐ for moles and particle count. It is useful for chemistry exercises and basic preparation planning when the substance's molar mass is already known.

How To Use It

  1. Choose whether to calculate mass, moles from mass, molar mass, particles from moles, or moles from particles.
  2. Enter the requested values using grams, moles, grams per mole, or a particle count as labeled. Mass, amount, and particle count may be zero; molar mass and any divisor must be positive.
  3. Review the formula and substituted values beneath the result to verify the conversion.
  4. For mass-based calculations, use the molar mass of the exact chemical formula and form you are working with.
  5. Round the result according to the precision of your measured or supplied data.

Examples

Grams to moles

5.844 g of a substance with molar mass 58.44 g/mol corresponds to 5.844 / 58.44 = 0.1000 mol.

Moles to grams

0.250 mol of a compound with molar mass 180.156 g/mol has mass 0.250 × 180.156 = 45.039 g.

Moles to particles

2.00 mol contains 2.00 × 6.02214076×10²³ = 1.204428152×10²⁴ specified entities.

Particles to moles

3.01107038×10²³ specified particles divided by Avogadro's constant corresponds to 0.500 mol.

Useful Notes

Mass, moles, and molar mass

The relationship n = m/M uses amount n in moles, mass m in grams, and molar mass M in grams per mole. Rearranging gives m = nM and M = m/n.

Avogadro's constant

One mole contains exactly 6.02214076×10²³ specified elementary entities. The entity may be atoms, molecules, ions, formula units, or another explicitly defined particle, so the chemical context matters.

Chemical identity matters

Molar mass must match the exact formula. An anhydrous compound and a hydrate, for example, have different molar masses. The calculator intentionally does not guess chemical identity from a name or formula.

Purity and mixtures

The direct mass-to-moles relationship assumes the entered mass represents the substance described by the entered molar mass. Samples with stated purity, mixtures, solutions, or formulations can require an additional composition calculation.

Not a stoichiometry solver

This tool converts quantities for one specified substance. Balanced-reaction mole ratios, limiting reagents, yields, and reaction products require stoichiometric information that is outside this calculator's scope.

Precision

Avogadro's constant is exact in the SI definition, but measured mass and tabulated molar mass have finite precision. Report results with significant figures appropriate to the least precise input.

FAQ

How do I convert grams to moles?

Divide mass in grams by molar mass in grams per mole: n = m/M.

How do I convert moles to grams?

Multiply the amount in moles by molar mass: m = nM.

How many particles are in one mole?

Exactly 6.02214076×10²³ specified elementary entities per mole.

How do I convert particles to moles?

Divide the specified particle count by Avogadro's constant, 6.02214076×10²³ mol⁻¹. Be clear whether the entities are atoms, molecules, ions, or formula units.

What counts as a particle?

It depends on what is specified: atoms, molecules, ions, formula units, electrons, or another entity. State the entity when interpreting a particle count.

Does this calculator find molar mass from a chemical formula?

No. It can solve molar mass from known mass and moles, but it does not parse formulas or maintain an atomic-weight table.