Dilution Calculator (C1V1=C2V2)

What is the Dilution Calculator (C1V1=C2V2)?

A dilution calculator works out the volumes needed to dilute a concentrated stock solution down to a target concentration, using the standard dilution equation C1V1 = C2V2, where C1 and V1 are the stock's concentration and volume, and C2 and V2 are the target concentration and final volume. It works by rearranging this equation depending on what you're solving for: to find how much stock solution to use (V1), the calculator computes V1 = (C2 × V2) ÷ C1; to find the final volume a given amount of stock will produce (V2), it computes V2 = (C1 × V1) ÷ C2. To work it out manually, plug your known values into whichever rearrangement of C1V1=C2V2 matches what you're solving for, always keeping concentration units and volume units consistent throughout.

How it works

The dilution equation C1V1 = C2V2 reflects a simple principle: the total amount of solute doesn't change when you dilute a solution, only its concentration does. C1 and V1 are the concentration and volume of your starting (stock) solution, while C2 and V2 are the concentration and volume you want to end up with — knowing any three of these four values lets you solve for the fourth.

UK context

This formula is used constantly across chemistry, biology, pharmacy and cleaning/industrial contexts wherever a concentrated stock solution needs to be diluted to a specific working concentration — getting it right matters because both under- and over-diluting can make a solution ineffective or, in some contexts, unsafe.

Tips

• Keep concentration units consistent on both sides of the equation (both in molarity, or both as a percentage, for example) — mixing units is a common source of dilution errors.
• The volume of diluent to add is the final volume minus the starting stock volume, not the final volume itself — a frequently confused step.

A quick note

Uses C1V1 = C2V2. Use consistent concentration and volume units throughout for an accurate result.