Solve the dilution equation C1V1 = C2V2 for any one value: stock concentration, stock volume, final concentration or final volume.
Concentrations must each use consistent units, and volumes must each use consistent units.
Dilution keeps the amount of solute the same while the volume increases, so the stock concentration multiplied by the stock volume equals the final concentration multiplied by the final volume: C1V1 = C2V2. Choose the value to solve for and enter the other three; the selected target field is ignored. Concentrations must all use one consistent unit (for example mol/L throughout) and volumes must all use one consistent unit (for example mL throughout) — the equation only balances when each pair shares a unit.
What does C1V1 = C2V2 mean? C1 and V1 are the concentration and volume of the stock solution, and C2 and V2 are the concentration and volume after dilution. The amount of solute is unchanged, so the two products are equal.
Which units should be used? Any units work as long as they are consistent: both concentrations in the same unit and both volumes in the same unit. Mixing mol/L with mmol/L, or mL with L, gives a wrong result.