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Mole Calculator (Grams to Moles to Molecules)

Choose a conversion and enter your value. The molar mass links grams to moles, and Avogadro's constant links moles to molecules.

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Formula

  • n = m ÷ MM (moles = mass in g ÷ molar mass in g/mol)
  • N = n × N_A with N_A = 6.02214076 × 10^23 per mol (exact, SI 2019)
  • Reverse: m = n × MM and n = N ÷ N_A

Worked example

36.03 g of water, molar mass 18.015 g/mol:

  1. Moles: 36.03 ÷ 18.015 = 2 mol
  2. Molecules: 2 × 6.02214076 × 10^23 = 1.204428152 × 10^24

Check the other way: 0.5 mol of CO2 (44.01 g/mol) has a mass of 0.5 × 44.01 = 22.005 g.

Frequently asked questions

How do I convert grams to moles?

Divide the mass in grams by the molar mass in g/mol. 36.03 g of water (18.015 g/mol) is 36.03 ÷ 18.015 = 2 mol.

How do I convert moles to molecules?

Multiply by Avogadro's constant, 6.02214076 × 10^23 per mole (an exact value since 2019). 2 mol of water is 1.204428152 × 10^24 molecules.

Where do I find the molar mass?

Add up the atomic weights of every atom in the formula. Carbon dioxide is 12.011 + 2 × 15.999 = 44.009, about 44.01 g/mol. The molar mass calculator does this for you.

Does the mole apply to atoms and ions too?

Yes. One mole is 6.02214076 × 10^23 of any specified entity: atoms, molecules, ions or formula units. For ionic compounds such as NaCl the count is of formula units.

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