How to calculate molarity
Molarity is the most common way to measure the concentration of a solution in chemistry. It is the number of moles of dissolved substance (the solute) per litre of solution. A higher molarity means a more concentrated solution.
The molarity formula
Molarity (M) = moles of solute / litres of solution. To get moles from a mass, divide the mass by the substance's molar mass first.
Worked example
Dissolving 2 moles of a substance in 1 litre of solution gives a molarity of 2 / 1 = 2 mol/L, written as 2 M.
Frequently asked questions
What is molarity?
The concentration of a solution: moles of solute divided by litres of solution, measured in mol/L (M).
How do I get moles from grams?
Divide the mass in grams by the molar mass of the substance. Our molar mass calculator finds that from a chemical formula.
What is the difference between molarity and molality?
Molarity is per litre of solution; molality is per kilogram of solvent. Molarity is far more common in everyday chemistry.