When you dilute a solution, the amount of solute stays the same — only the volume changes. That gives the dilution equation C₁V₁ = C₂V₂. Enter any three values to find the fourth, using the same concentration unit for C₁ and C₂ (M, mg/mL, % and so on).
Formula
C1 × V1 = C2 × V2
Where C1 is the stock concentration (c₁), V1 is the stock volume (v₁) (mL), C2 is the final concentration (c₂), V2 is the final volume (v₂) (mL).
Choose any value to calculate — the calculator rearranges the formula for you.
Worked example
To make 250 mL of a 1 M solution from a 10 M stock: V₁ = C₂V₂ ÷ C₁ = 1 × 250 ÷ 10 = 25 mL of stock, topped up with 225 mL of solvent.
Frequently asked questions
What does C1V1 = C2V2 mean?
Initial concentration × initial volume = final concentration × final volume. It holds because diluting adds solvent but no solute.
Do the units matter?
Use the same unit for both concentrations and the same unit for both volumes. The equation works with any consistent units.
Last updated · Calculations checked by automated tests· Editorial policy