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Dilution Calculator

Dilution is the process of adding solvent (usually water) to lower a solution's concentration. Since the amount of solute does not change, the product of concentration and volume stays the same before and after dilution (C1V1 = C2V2).

Enter the initial concentration and volume and the target concentration to calculate the final volume and the amount of solvent (water) to add.

For example, to dilute 100 mL of a 5 M solution to 1 M, the final volume must be 500 mL, so 400 mL of water must be added.

Dilution Calculator Calculation Method

C_1 V_1 = C_2 V_2
C1,V1: initial concentration and volume, C2,V2: target concentration and final volume
Final volume (V2): 0 mL
Water to add: 0 mL

About This Calculator

Dilution adds solvent to a solution to reduce its concentration while keeping the amount of solute constant. Because the moles do not change, concentration and volume are inversely related.

Enter the initial concentration and volume and the target concentration to find the final volume and how much solvent (water) to add.

Dilution keeps the amount of solute constant while the volume grows, so the concentration falls in exact proportion to the volume added. Preparing 500 mL of 0.1 mol/L solution from a 2 mol/L stock needs 25 mL of stock made up to the mark. In practice the limiting factor is glassware accuracy: a 25 mL pipette is far more precise than a 25 mL measuring cylinder.

Key Formula:C₁ × V₁ = C₂ × V₂

Frequently Asked Questions

What is the dilution equation?

C₁V₁ = C₂V₂, where C is concentration and V is volume. It follows from the fact that diluting changes only the volume, not the number of moles of solute.

How do I dilute a stock solution in the lab?

Calculate the final volume, measure the required amount of stock, add it to a volumetric flask, then fill to the mark with solvent and mix. Always add concentrated acid to water, never the reverse.

Does dilution change the number of moles of solute?

No. Only solvent is added, so the moles stay the same and the concentration drops as the volume rises. That is exactly why C1 × V1 = C2 × V2 works: both sides equal the same number of moles.

How do I express the dilution factor?

Divide the final volume by the stock volume: 25 mL into 500 mL is a 20-fold dilution, written 1:20. Serial dilutions multiply, so three consecutive 10-fold steps give 1:1000 overall.

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Sources & last update

2026-10-19