Dilution Calculator
Dilution calculator works out Stock volume to take (V1) and Solvent to add from Stock concentration (C1), Stock volume (V1) and Final concentration (C2). The default figures on this page give stock volume to take (V1) of 20.000000; change any entry and the result, the working and the sources update together.
Your figures
Updates as you typeHow this is worked out
3 steps
- V1 = C2 x V2 / C1 = 2 x 100 / 10 = 20
- Solvent to add = V2 - V1 = 100 - 20 = 80
- Dilution factor = C1 / C2 = 5 -fold
Its 5 worked examples are re-run on every release, last on 15 September 2026. What changed
Sources and references
3 sources
What the dilution calculator calculates
Solves C1 V1 = C2 V2 for the stock volume, solvent to add, finished volume or either concentration, and builds a serial dilution schedule.
How to use this dilution calculator
Enter Stock concentration (C1), Stock volume (V1), Final concentration (C2) and Final volume (V2). Stock volume to take (V1) updates as you type, and “Use a worked example” loads checked figures you can adjust. Change one figure at a time to see what drives the result.
How the result is worked out
Open “How this is worked out” beside the result for the step-by-step calculation behind Stock volume to take (V1), Solvent to add and Final volume (V2).
The method follows OpenStax Chemistry 2e, section 3.3 Molarity - Dilution of Solutions, IUPAC Compendium of Chemical Terminology (Gold Book), "dilution" and US Pharmacopeia General Chapter <1151> on preparing solutions to a final volume.
Research fixture R3570-GT-1: 10 down to 2 in 100 example
With Stock concentration (C1): 10, Final concentration (C2): 2, Final volume (V2): 100, the calculator returns Stock volume to take (V1): 20, Solvent to add: 80, Dilution factor: 5. This example is checked against an independent source in the test suite.
What you can compare
Change one input at a time to see how it affects Stock volume to take (V1), Solvent to add and Final volume (V2). The inputs you can vary are Stock concentration (C1), Stock volume (V1), Final concentration (C2), Final volume (V2), Solve for and Concentration unit.
Understanding Stock volume to take (V1), Solvent to add and Final volume (V2)
Add the stock to the solvent and make the solution up to the final volume; volumes of mixed liquids are not exactly additive. Verify the result before preparing reagents that will be dosed or assayed.
Results are general information, not financial, tax, legal, medical or engineering advice. Check any decision that matters with a qualified professional.
See something wrong? Report a problem with this calculator
Frequently asked questions
How to calculate a dilution?
Solves C1 V1 = C2 V2 for the stock volume, solvent to add, finished volume or either concentration, and builds a serial dilution schedule. Open “How this is worked out” beside the result to see each step for your own figures.
How to make a 1:20 dilution?
It needs Stock concentration (C1), Stock volume (V1), Final concentration (C2), Final volume (V2), Solve for and Concentration unit. Nothing else is required, and the figures stay in your browser.
What is a 1:50 dilution?
Solves C1 V1 = C2 V2 for the stock volume, solvent to add, finished volume or either concentration, and builds a serial dilution schedule. On this page it is computed from Stock concentration (C1), Stock volume (V1) and Final concentration (C2) and shown as Stock volume to take (V1), Solvent to add and Final volume (V2).
What information do I need for the dilution calculator?
You need Stock concentration (C1), Stock volume (V1), Final concentration (C2), Final volume (V2), Solve for, Concentration unit, Serial dilution steps and Fold dilution per serial step. The page opens with default figures that give stock volume to take (V1) of 20.000000, so you can see the scale before entering your own.
What does this dilution calculator show?
It shows Stock volume to take (V1), Solvent to add, Final volume (V2), Stock concentration (C1), Final concentration (C2), Dilution factor, Concentration unit and Serial dilution schedule, with the working and any warnings for your entries.
Can I check how the dilution calculator result was calculated?
Yes. The “How this is worked out” section shows the calculation steps, and the sources section identifies the references used for the method.