Dilution Calculator

C1V1 = C2V2, solved for whichever value you leave blank.

Why the equation works

Adding solvent changes the volume but not the amount of solute. Concentration times volume is the quantity of solute, so that product is the same before and after. That is the entire derivation, and it is why the equation holds for any concentration unit as long as both sides use the same one.

Worked example

To make 100 mL of 2 M from a 10 M stock: V₁ = (2 × 100) ÷ 10 = 20 mL of stock, made up to 100 mL total — so 80 mL of solvent is added. The calculator reports both the stock volume and the diluent to add, because that second number is the one you actually pipette.

Add acid to water, never the reverse

Diluting concentrated acid releases a lot of heat. Adding water to acid concentrates that heat at the surface and can boil it, spitting acid out of the vessel. Adding acid slowly into a larger volume of water disperses the heat. This is a safety rule, not a preference.

Serial dilution

To reach a very low concentration, dilute in steps. Each 1-in-10 step multiplies the dilution factor, so three steps give 1:1000. This is more accurate than one large dilution, because measuring 100 µL accurately is easier than measuring 0.1 µL, and it is standard practice for preparing microscope specimens and microbiological cultures.