Molarity Calculator
Find the molar concentration of a solution from the mass of solute, its molar mass, and the solution volume.
The formula
Moles = mass (g) ÷ molar mass (g/mol). Molarity = moles ÷ volume (L).
Worked example
5.85 g of table salt (NaCl, molar mass 58.5 g/mol) dissolved in 0.5 L of water gives 5.85 ÷ 58.5 = 0.1 mol of NaCl, and a molarity of 0.1 ÷ 0.5 = 0.2 mol/L.
Frequently asked questions
Where do I find a compound's molar mass?
Add up the atomic masses of every atom in the chemical formula from a periodic table — for example, NaCl is Na (≈23) + Cl (≈35.5) = 58.5 g/mol.
Does volume mean the volume of solute or the whole solution?
The whole solution's final volume after the solute is dissolved and made up to volume — not just the volume of solvent added.