Molarity (symbol M, units mol/L) is the number of moles of solute dissolved per litre of solution. This calculator solves for molarity, the mass of solute to weigh out, or the volume of solution to prepare — for chemistry students and anyone making up solutions in the lab.
How it works
Molarity links concentration, mass and volume through:
M = moles ÷ litres = mass ÷ (molar mass × volume in litres)
Pick which quantity to solve for and the tool rearranges the formula:
- Molarity = mass ÷ (molar mass × volume)
- Mass = molarity × molar mass × volume
- Volume = mass ÷ (molarity × molar mass)
You can enter volume in litres or millilitres (mL is divided by 1000 internally).
Example
To prepare 1 L of 0.5 M sodium chloride (NaCl, molar mass 58.44 g/mol):
mass = 0.5 × 58.44 × 1 = 29.22 g. Weigh out 29.22 g of NaCl and make it up to 1 litre.
| Solve for | Formula |
|---|---|
| Molarity | mass ÷ (molar mass × volume) |
| Mass | molarity × molar mass × volume |
| Volume | mass ÷ (molarity × molar mass) |
Every calculation runs locally in your browser and nothing is uploaded.