Dilution Calculator

How to use the Dilution Calculator

1. 1Enter three of the four values C1, V1, C2 and V2.
2. 2Pick the units or options from the menus if the dilution tool offers them.
3. 3Read the dilution in the large result box.
4. 4Look at the extra rows for related figures.
5. 5Press Copy result to keep the answer.

When you need the dilution

Chemistry and biology students, lab workers and cooks making cordials or cleaning mixes use it to prepare solutions.

The equation works with any concentration unit as long as both concentrations use the same one, and any volume unit if both volumes match. The stock must always be more concentrated than the final solution.

How the dilution is worked out

C1 × V1 = C2 × V2, so for example V1 = C2 × V2 ÷ C1. The solvent to add is V2 − V1. To make 500 mL of a 2 M solution from a 10 M stock you need V1 = 2 × 500 ÷ 10 = 100 mL of stock, and 400 mL of water.

Every answer on this page comes from that one rule, so you can check any result by hand with a calculator. The figures shown underneath, such as other units, are conversions of the same answer.

• Solve for any one value
• Solvent to add
• Any units

Mistakes to avoid with dilution

Add the stock to the solvent and not the other way round for strong acids, and always follow safety rules. The equation assumes volumes are additive, which is close for dilute solutions.

On phone and computer

On a phone, type into the boxes one after another and read the dilution underneath; Copy result puts it on the clipboard for a message or a note. On a computer the inputs sit on the left and the answer on the right, so you can change one figure and watch the dilution move. The dilution calculator works the same on both.

Checking your dilution by hand

A good habit is to test the dilution calculator with a case you already know. To make 500 mL of a 2 M solution from a 10 M stock you need V1 = 2 × 500 ÷ 10 = 100 mL of stock, and 400 mL of water.

If your own figures give a surprising answer, repeat the working yourself: C1 × V1 = C2 × V2, so for example V1 = C2 × V2 ÷ C1. The solvent to add is V2 − V1. Small differences usually come from rounding, from mixing units, or from a typing slip in one of the inputs. Mixing a solution usually needs a second check on strength and amount. Work out the final strength with the Solution Concentration Calculator, find moles with the Molarity Calculator, and turn parts into shares with the Percentage Calculator.

Features

• Matching units
• Stock must be stronger
• Safety first with acids
• Clear messages when the dilution inputs make no sense
• Copy the result with one tap
• Private: nothing is uploaded

Frequently asked questions