Solution Dilution Calculator
Enter your stock concentration, target concentration, and final volume to get the stock volume to measure out and the diluent to add — straight from C₁V₁ = C₂V₂.
Stock and diluent at once
This dilution calculator returns both numbers you need: the stock volume to pipette (V₁) and the solvent to add (V₂ − V₁) to reach your final volume.
Keep units consistent
Both concentrations must share one unit and both volumes another — molarity, percent, or fold for concentration; mL or L for volume.
What is a dilution calculator?
Solving C₁V₁ = C₂V₂
A dilution calculator works out how to turn a concentrated stock solution into a more dilute one of a known concentration and volume. It rearranges the dilution equation C₁V₁ = C₂V₂ to give the stock volume you must measure out, V₁ = (C₂ × V₂) ÷ C₁, and then the diluent (solvent) you add to reach the final volume, V₂ − V₁. It is the everyday calculation behind preparing buffers, reagents, cleaning solutions, and lab dilutions.
Enter the stock concentration, the target concentration, and the final volume to get the stock volume to measure and the diluent to add instantly.
The dilution equation says the amount of solute is unchanged by adding solvent, so concentration times volume stays constant. Rearranging for the stock volume gives the formula below; the diluent is whatever is left to reach the final volume.
V₁ = (C₂ × V₂) ÷ C₁Once you know V₁, the diluent to add is simply V₂ − V₁. Because both sides of C₁V₁ = C₂V₂ use the same concentration unit and the same volume unit, the units cancel — use whatever you like, as long as you stay consistent, and the answers return in your volume unit.
Suppose you have a 10× stock and want 100 mL of a 2× working solution.
Multiply the target by the final volume
C₂ × V₂ = 2 × 100 = 200 — the solute amount the final solution must contain.
Divide by the stock concentration
200 ÷ 10 = 20 mL — the stock volume (V₁) to measure out.
Find the diluent
100 − 20 = 80 mL — the solvent to add. Combine 20 mL of stock with 80 mL of solvent to get 100 mL of 2× solution.
The equation is exact, but a couple of practical points are worth keeping in mind.
You cannot concentrate by diluting, and mixing is non-ideal
Diluting only lowers concentration, so the final concentration C₂ must be less than or equal to the stock concentration C₁ — asking for a stronger result returns nothing, because that needs evaporation or more solute, not solvent. The diluent volume also assumes volumes add up exactly; for concentrated acids or alcohol–water mixes the real combined volume can differ slightly, so make up to the final volume in a graduated vessel rather than just adding V₂ − V₁ blind.