Dilution Calculator

The Dilution Equation is one of the most fundamental relationships in chemistry. It states that the number of moles of solute stays constant when you add more solvent to a solution.

C1 × V1 = C2 × V2

Variable definitions:

• C1 = concentration of the stock (starting) solution
• V1 = volume of stock solution to use
• C2 = desired concentration of the final diluted solution
• V2 = total volume of the final diluted solution

Solving for any missing variable:

• V1 = (C2 × V2) / C1
• C2 = (C1 × V1) / V2
• V2 = (C1 × V1) / C2
• C1 = (C2 × V2) / V1

Units must match on both sides. Use the same concentration unit (M, mM, %, g/L) and the same volume unit (mL, L) throughout.

Worked example: You have a 5 M stock solution of NaCl. You need 500 mL of a 0.25 M solution for an experiment.

• V1 = (0.25 × 500) / 5 = 25 mL of stock
• Add 25 mL of stock to a volumetric flask, then bring total volume to 500 mL with distilled water

Dilution factor = C1 / C2 = 5 / 0.25 = 20× — meaning the solution is 20 times more dilute.

Common lab concentrations:

• Bleach disinfectant: dilute 1:10 (1 part bleach, 9 parts water)
• HCl 1M from 12M stock: dilute ~1:12
• BSA protein standard series: 2-fold serial dilutions

Safety note: When diluting acids, always add acid to water — never the reverse. This prevents dangerous exothermic splashing.