Dilution Calculator
Find the final volume for a target concentration.
Results update as you type.
How it works
Diluting a concentrated stock solution to a weaker working concentration is one of the most common tasks in any laboratory, and this dilution calculator handles it using the classic relationship C-one V-one equals C-two V-two. You enter the concentration and volume of your stock solution and the concentration you want to end up with, and it returns the final volume you need and how much solvent, such as water or buffer, to add. The principle is that adding solvent does not change the total amount of dissolved solute, only how spread out it is, so the product of concentration and volume is conserved. This works with any consistent pair of units, whether the concentration is in molarity, percent, milligrams per millilitre, or parts per million, as long as both concentrations use the same unit and both volumes use the same unit. Chemists, biologists, pharmacists, and students preparing reagents rely on this calculation daily to make standards, working solutions, and serial dilutions accurately. Getting it right matters because an incorrect dilution can ruin an experiment or, in a clinical setting, a dose. Enter the three known values and the calculator gives the final volume and the amount of solvent to add.
C₁V₁ = C₂V₂ → V₂ = C₁V₁ / C₂
The dilution equation states that the amount of solute stays constant when you add solvent, so the concentration times the volume before dilution equals the concentration times the volume after. Rearranging gives the final volume as the stock concentration times its volume, divided by the target concentration. The extra solvent you must add is simply the final volume minus the starting volume, since only solvent is added and no solute is removed.
Source:Chemistry (dilution equation)
We review all our tools from time to time to ensure accuracy.
Worked example
How to use this calculator
- 1
Enter your values
Enter stock concentration (c₁), stock volume (v₁) and target concentration (c₂).
- 2
Adjust the options
Fine-tune any options to match your situation.
- 3
Read your result
Final volume (V₂) updates instantly as you type — no button to press.
Frequently asked questions
What is the dilution formula?
The dilution formula is C-one times V-one equals C-two times V-two, where C-one and V-one are the concentration and volume of the stock solution, and C-two and V-two are the concentration and volume after dilution. It works because adding solvent keeps the amount of solute constant. Rearranging lets you solve for whichever quantity is unknown, most often the final volume.
How much solvent should I add?
First find the final volume using the dilution equation, then subtract the volume of stock you started with. The difference is the amount of solvent to add, because dilution only involves adding solvent, never removing solute. For example, diluting two units of stock up to a final volume of five units means adding three units of solvent to the original two.
What units can I use?
Any consistent units work, as long as both concentrations share one unit and both volumes share another. Concentration can be molarity, percent, milligrams per millilitre, or parts per million, and volume can be millilitres, litres, or microlitres. The formula relies only on ratios, so it does not matter which specific units you pick, provided you do not mix different units within the same pair.
What is a serial dilution?
A serial dilution is a sequence of dilutions where the diluted solution from one step becomes the stock for the next, producing a geometric decrease in concentration, such as tenfold at each stage. It is used to create a range of concentrations for standard curves and to count microorganisms. Each individual step still follows the same C-one V-one equals C-two V-two relationship.
Why is accurate dilution important?
Concentration directly affects experimental results, chemical reactions, and, in medicine, the dose a patient receives. A dilution error can produce misleading data, failed reactions, or unsafe medication concentrations. Using the dilution equation ensures the working solution has exactly the intended strength, which is essential for reproducibility in research and for safety in clinical and pharmaceutical settings.