Molarity Dilution Calculator
Preparing a working solution from a concentrated stock is one of the most common bench tasks. The dilution equation C1V1 = C2V2 tells you exactly how much stock to draw because the moles of solute do not change when you add solvent. This calculator takes your stock concentration, target concentration, and target volume, and returns the stock volume to pipette and the diluent volume to add. Keep concentration units the same and volume units the same on both sides.
Dilution formula
C1 * V1 = C2 * V2
V1 = (C2 * V2) / C1
Diluent = V2 - V1
Dilution factor = C1 / C2
Pipette V1 of stock, then add diluent up to the target volume V2. The dilution factor is how many times more dilute the final solution is than the stock.
Worked example
From a 1 molar stock, prepare 500 mL of 0.1 molar: V1 = (0.1 * 500) / 1 = 50.00 mL of stock. Diluent = 500 - 50 = 450.00 mL. Dilution factor = 1 / 0.1 = 10.00, a tenfold dilution.
Molarity dilution: frequently asked questions
What is the dilution equation?
The dilution equation is C1 times V1 equals C2 times V2, where C1 and V1 are the concentration and volume of the stock solution and C2 and V2 are the concentration and volume of the diluted solution. The moles of solute stay constant, so adding solvent lowers concentration.
How much stock solution do I need?
Rearrange the dilution equation to V1 = C2 times V2 divided by C1. For a 0.1 molar, 500 mL target from a 1 molar stock, V1 = 0.1 * 500 / 1 = 50 mL of stock, topped up to 500 mL with diluent.
Does this work for any concentration unit?
Yes, as long as both concentrations use the same unit (molarity here) and both volumes use the same unit. The equation only requires the units to match on each side; it does not depend on the specific unit chosen.
Sources
- NIST: SI units, including the mole and litre.
- The dilution equation C1V1 = C2V2 expresses conservation of moles of solute; no external figure is required.
Reviewed by the CalculatorHub team, edited by James Graham, 19 June 2026. See our methodology.