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Grams to Moles Calculator

Convert a mass in grams to an amount in moles. Enter the mass and the molar mass of the substance — or type a chemical formula to look the molar mass up automatically — and the calculator divides one by the other to give the number of moles.

Mass
g
Compound
Element
Chemical formula
Molar mass
g/mol

How to Convert Grams to Moles

Divide the mass of the sample in grams by the molar mass of the substance in grams per mole. The grams cancel and you are left with moles.

You need the molar mass first — find it by adding the atomic weights of every atom in the formula, or use the molar mass calculator.

Formula

moles = mass (g) ÷ molar mass (g/mol)

Example: Convert 36 g of water to moles (M = 18.015 g/mol):

36 ÷ 18.015 = 1.998 mol


See also