Dilution Calculator

Solve C₁V₁ = C₂V₂ for any value, with molar, mass, percent, and fold units. Includes a serial dilution planner.

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How to Use the Dilution Calculator

Pick the value you want to find with the Solve for buttons — most often V₁, the volume of stock to measure out. Enter the other three values and choose a unit for each. The result appears as you type, together with the dilution factor, the volume of diluent (water, buffer, or solvent) to add, and a one-line mixing instruction. Use the example chips to load common lab dilutions. For a dilution series, switch to the Serial dilution tab, enter the starting concentration, the dilution factor per step, the number of tubes, and the final volume you want in each tube.

About This Tool

The dilution equation C₁V₁ = C₂V₂ follows from one simple fact: adding solvent changes the volume of a solution but not the amount of solute in it. The amount of solute in the stock you measure out (C₁ × V₁) must equal the amount in the finished solution (C₂ × V₂). Rearranging gives V₁ = C₂V₂ ÷ C₁, which is the form most people need at the bench: how much stock goes into the final volume.

The equation works with any concentration unit as long as C₁ and C₂ are expressed in the same kind of unit. This calculator converts within each family automatically — molarity (M, mM, µM, nM), mass per volume (g/L, mg/mL, µg/mL, ng/mL), percent, and fold (×) for buffers sold as 10× or 50× concentrates. Each volume can use its own unit, so you can enter a final volume in millilitres and get the stock volume back in microlitres. It cannot convert between molarity and mass concentration, because that needs the molecular weight of the solute.

A serial dilution repeats the same dilution several times in a row, which is how labs reach very low concentrations accurately for standard curves, MIC assays, and plate counts. Each tube is diluted by the same factor from the one before, so after n steps the total dilution is factorⁿ. The planner gives the transfer and diluent volume for every tube and the concentration in each. All calculations run in your browser. For other proportion work you can calculate a percentage or use the scientific calculator for molecular weight conversions.

Quick Reference Table

Dilution	Factor	Stock per 10 mL	Diluent per 10 mL
1:2	2×	5 mL	5 mL
1:5	5×	2 mL	8 mL
1:10	10×	1 mL	9 mL
1:20	20×	500 µL	9.5 mL
1:50	50×	200 µL	9.8 mL
1:100	100×	100 µL	9.9 mL
1:1000	1000×	10 µL	9.99 mL

Frequently Asked Questions

What does C1V1 = C2V2 mean?

C₁ is the concentration of your stock solution and V₁ is the volume of stock you use. C₂ is the concentration you want and V₂ is the final volume. Because diluting does not change the amount of solute, C₁ × V₁ equals C₂ × V₂. Know any three and you can solve for the fourth.

Is V2 the volume of water I add?

No. V₂ is the total final volume, including the stock. The volume of diluent to add is V₂ − V₁. For example, to make 100 mL of a 1:10 dilution you add 10 mL of stock to 90 mL of water, not to 100 mL. The calculator shows the diluent volume separately.

What is the difference between a 1:10 dilution and a 1 to 10 ratio?

In lab usage, a 1:10 dilution normally means 1 part stock in 10 parts total (1 part stock + 9 parts diluent), which is a dilution factor of 10. Some fields, such as mixing cleaning concentrates, use 1:10 to mean 1 part concentrate to 10 parts water (11 parts total). This calculator uses the lab convention.

Can I use different units for C1 and C2?

Yes, as long as they are the same kind of unit. You can dilute a 1 M stock to 10 mM, or a 1 mg/mL stock to 5 µg/mL, and the calculator converts automatically. Converting between molarity and mg/mL needs the molecular weight of the compound: mg/mL = M × molecular weight (g/mol).

How do I calculate a serial dilution?

Choose a dilution factor per step and a final volume per tube. Each tube gets final volume ÷ factor of the previous solution, topped up with diluent to the final volume. With a 10× factor and 1 mL tubes, transfer 100 µL into 900 µL of diluent each time. After n tubes, the concentration is the starting concentration divided by factorⁿ.

Created by The Toobits Team · Engineering & Editorial

Toobits is built, tested, and maintained by a small independent engineering team. Every tool is written in TypeScript, runs entirely in the browser, and is reviewed against its source formulas before publication.

Editorial policy · Updated October 2026