Convert between moles, mass, and number of particles with this Mole Calculator. Enter any two of the three values — mass (grams), molecular weight (g/mol), or moles — and the calculator solves for the third. You also get the number of molecules or atoms using Avogadro's number. Perfect for chemistry students and engineers working with stoichiometry and unit conversions.
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Moles
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Mass
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Molecular Weight
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Number of Particles
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A mole is a unit of measurement used in chemistry to express amounts of substance. One mole contains exactly 6.02214076 × 10²³ elementary entities (Avogadro's number), which can be atoms, molecules, ions, or other particles. It bridges the atomic scale with measurable, macroscopic quantities.
To find the number of moles, divide the mass of the substance (in grams) by its molecular weight (in g/mol): moles = mass ÷ molecular weight. For example, 10 g of HCl (molecular weight 36.5 g/mol) gives 10 ÷ 36.5 ≈ 0.274 moles.
Multiply the number of moles by the molecular weight of the substance: mass (g) = moles × molecular weight (g/mol). For example, 0.274 moles of NaOH (molecular weight 40 g/mol) equals 0.274 × 40 = 10.96 grams.
The molar mass is found by summing the atomic masses of all atoms in the molecular formula. Atomic masses are found on the periodic table. For example, water (H₂O) has a molar mass of 2(1.008) + 15.999 ≈ 18.015 g/mol.
One mole of any substance contains 6.02214076 × 10²³ atoms, molecules, or particles — this is Avogadro's number. So 1 mole of carbon atoms contains approximately 6.022 × 10²³ carbon atoms.
It depends on the substance. The number of grams per mole equals the molecular weight of that substance. For example, 1 mole of water is about 18 grams, 1 mole of NaCl is about 58.44 grams, and 1 mole of iron is about 55.85 grams.
Yes. If you know both the mass of a sample and the number of moles it contains, you can select 'Molecular Weight' in the Solve For dropdown and the calculator will compute the molar mass as mass ÷ moles.
Avogadro's number (6.02214076 × 10²³) is the number of particles in one mole of a substance. It matters because atoms and molecules are incredibly tiny, so chemists use moles and Avogadro's number to relate measurable macroscopic quantities (like grams) to the actual count of particles in a sample.