Enter your substance's Mass and Molecular Weight (or let the calculator fetch it automatically by typing a Chemical Formula), and you'll get the Amount in Moles, the Number of Molecules, and a Calculated Mass back in seconds.
Amount in Moles
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Number of Molecules
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Calculated Mass
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A mole is a unit of measurement used in chemistry to express amounts of a chemical substance. One mole contains exactly 6.022 × 10²³ particles (Avogadro's number), whether atoms, molecules, ions, or electrons.
To calculate moles, divide the mass by the molecular weight: moles = mass (g) ÷ molecular weight (g/mol). For example, 18g of water (H₂O) with molecular weight 18.015 g/mol equals 0.999 moles.
Find the molar mass by adding the atomic masses of all atoms in the compound's formula. For H₂O: (2 × 1.008) + (1 × 15.999) = 18.015 g/mol. Use the periodic table for atomic masses.
One mole contains exactly 6.022140876 × 10²³ molecules, known as Avogadro's number. This constant allows chemists to count particles by weighing them instead of counting individually.
Divide the mass in grams by the substance's molar mass in g/mol. The formula is: moles = grams ÷ molar mass. Make sure you know the correct molar mass of your compound first.
Molecular weight is the mass of one molecule in atomic mass units (amu), while molar mass is the mass of one mole in grams. Numerically they're equal, but molar mass has units of g/mol.
Atoms and molecules are incredibly small and numerous. Using moles allows chemists to work with measurable quantities while maintaining the correct proportions for chemical reactions. It's like using 'dozen' for eggs.