Grams to Moles Calculator
Convert a mass in grams to moles using molar mass, and see how many molecules that is.
How it works
moles = mass (g) ÷ molar mass (g/mol) · molecules = moles × 6.022×10²³
Molar mass is the conversion factor between the mass you weigh on a balance and the amount of substance in moles. Dividing grams by the molar mass gives moles; multiplying the result by Avogadro's number gives the actual count of molecules or formula units. It is the reverse of the moles-to-grams conversion.
Worked example
For 18 g of water (molar mass 18.015 g/mol): 18 ÷ 18.015 ≈ 0.999 mol, containing about 6.02×10²³ molecules — very close to one mole.
Sources: Mole (unit) — Wikipedia
Frequently asked questions
Where do I find the molar mass?
Add up the atomic masses in the formula, or use the molecular weight calculator. Water is 18.015 g/mol, NaCl 58.44 g/mol and glucose 180.16 g/mol.
What is a mole?
A mole is 6.022×10²³ particles. It lets chemists count enormous numbers of atoms or molecules by weighing a convenient, measurable mass instead.
Does this work for elements too?
Yes. Use the element's atomic mass as the molar mass — 12.011 g/mol for carbon, for example — and the same division applies.
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