Calculate molarity, the mass of solute needed for a solution, and dilutions with C₁V₁ = C₂V₂.
Molarity (M) = moles of solute ÷ litres of solution. Dissolving 5.844 g of NaCl (58.44 g/mol) in 1 L gives 0.1 M. For dilutions use C₁V₁ = C₂V₂.
Molarity is the number of moles of solute per litre of solution — the standard way to state a solution's concentration in chemistry. This page has three calculators: molarity from the mass of solute, molar mass and volume; the mass of solute to weigh out for a target molarity and volume; and a dilution calculator based on C₁V₁ = C₂V₂ where you leave one value blank to solve for it.
Concentrations can be entered in M, mM or µM and volumes in litres, millilitres or microlitres. You need the compound's molar mass — find it with the Molecular Weight Calculator.
The calculations use moles as the common currency.
| Question | Answer |
|---|---|
| 5.844 g NaCl in 1 L — molarity | 0.1 mol/L |
| Mass of NaCl for 250 mL of 0.5 M | 7.305 g |
| Dilute 12 M stock to 1 M, 500 mL — stock needed | 41.666667 mL |
| 2 M × 100 mL diluted to 400 mL — final M | 0.5 M |
| Substance | Molar mass (g/mol) | 0.1 M | 1 M |
|---|---|---|---|
| NaCl | 58.44 | 5.844 g | 58.44 g |
| NaOH | 40 | 4.000 g | 40.00 g |
| KCl | 74.55 | 7.455 g | 74.55 g |
| Glucose (C₆H₁₂O₆) | 180.156 | 18.016 g | 180.16 g |
| CaCl₂ | 110.98 | 11.098 g | 110.98 g |
Weigh the solute, dissolve it in less solvent than the final volume, then transfer to a volumetric flask and top up to the mark so the total volume is exact. When diluting acids, add the acid to water slowly — never water to concentrated acid — and wear suitable protective equipment.
The concentration of a solution in moles of solute per litre of solution (mol/L, written M).
Divide the moles of solute by the volume of solution in litres. Moles are the mass divided by the molar mass.
Multiply the molarity by the volume in litres and by the molar mass. 0.5 M NaCl in 250 mL needs 7.305 g.
The dilution equation: concentration times volume of the stock equals concentration times volume of the diluted solution.
Calculate the stock volume V₁ = C₂V₂ ÷ C₁, measure it, and add solvent up to the final volume V₂.
Molarity is moles per litre of solution; molality is moles per kilogram of solvent. Molality does not change with temperature.
Yes — choose the units next to each box and the calculator converts them.
Add the atomic masses in the formula, or use the Molecular Weight Calculator.
Dilution only lowers concentration; the final volume equals the stock plus added solvent.
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