Molarity Calculator

Molarity describes the concentration of a solution as moles of solute per litre of solution. Give this calculator any two of molarity, moles, and volume and it solves for the third using M = mol ÷ L. It is built for chemistry students and lab workers preparing solutions, diluting stock reagents, or scaling a recipe up or down.

Formula

M = moles ÷ volume

M

Molarity, the concentration in moles per litre (mol/L)

moles

Amount of solute in moles (mol)

volume

Volume of the solution in litres (L)

How it works

1. Provide exactly two of the three quantities: molarity (mol/L), moles of solute, or volume in litres.
2. The calculator rearranges M = moles ÷ volume to solve for the missing value — volume = moles ÷ molarity, or moles = molarity × volume.
3. It returns all three values so you can read off the complete solution specification.

Worked example

Frequently asked questions

What is molarity?

Molarity is the number of moles of dissolved solute per litre of solution, written with the unit M (mol/L). A 1 M solution contains one mole of solute in every litre of total solution volume.

How many values do I need to enter?

Exactly two of molarity, moles, and volume. With any two known, the calculator solves for the third; supplying only one or all three is rejected with an error.

Is molarity the same as molality?

No. Molarity is moles of solute per litre of solution, while molality is moles of solute per kilogram of solvent. Molarity changes slightly with temperature because volume expands, whereas molality does not. This tool computes molarity.

How do I convert grams of solute into moles for this calculator?

Divide the mass in grams by the substance's molar mass in g/mol to get moles, then enter that value. A molecular weight calculator can supply the molar mass from a chemical formula.

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