Dilution Factor Calculator

Our Dilution Factor Calculator has two modes. Here's how to use each:

Mode 1 — C₁V₁ = C₂V₂: Enter any three of the four values (C₁, V₁, C₂, V₂) and leave the unknown field empty. Click 'Calculate Missing Value' to solve for it.

Mode 2 — Dilution Factor: Enter the initial volume (V₁) and the final volume (V₂), then click 'Calculate Dilution Factor' to get the factor as a multiplier.

Tip: Make sure all concentrations use the same unit and all volumes use the same unit before entering values. The calculator will automatically identify the missing variable and compute it.

The two core equations behind this calculator are:

C₁V₁ = C₂V₂ (conservation of moles)

Where: - C₁ = Initial concentration - V₁ = Initial volume - C₂ = Final concentration - V₂ = Final volume

This equation states that the number of moles of solute before and after dilution remains constant — only the volume changes, which lowers the concentration.

Dilution Factor = V₂ / V₁

This tells you how many times larger the final solution is compared to the original. For example, if V₁ = 10 mL and V₂ = 100 mL, the dilution factor is 10× — meaning the concentration was reduced tenfold.

A dilution is the process of lowering the concentration of a solution by adding more solvent. The molecules of solute are not removed or destroyed — they simply spread out across a larger volume, making each unit of solution less concentrated. This distinction matters because it means the total amount of solute (in moles) is always conserved across a dilution, which is the principle behind C₁V₁ = C₂V₂.

The dilution factor describes how much a solution has been scaled down. It is expressed as a ratio — either stock to dilutant (S:D) or stock to total solution (S:T). For example, mixing 10 mL of a stock solution with 90 mL of water gives a 1:9 S:D ratio, or a 1:10 S:T ratio. The S:T form is the most common in scientific and clinical contexts, and it is the form this calculator uses when computing V₂/V₁.

Dilutions appear throughout science and everyday life. In the laboratory, they are used to bring highly concentrated stock solutions down to usable working concentrations before running assays or reactions. In medicine, dilutions are used to adjust drug concentrations for patient dosing — for example, calculating the correct paracetamol dose per kilogram of body weight for a child often requires diluting a concentrated stock. Even food preparation involves dilutions: brewing coffee or tea, making squash, or diluting a sauce are all dilutions in practice.

When a single dilution does not achieve the desired concentration, serial dilutions are used — a chain of sequential dilutions where each step uses the output of the previous one as its new stock. This technique is widely used in microbiology, immunology, and pharmaceutical research to test samples across a broad range of concentrations efficiently.