Dilution Ratio Calculator
Work out how much stock and how much diluent to mix for a target concentration using C1V1 = C2V2, with the dilution factor expressed as a 1:X ratio.
How it works
C1 × V1 = C2 × V2 · V1 = C2 × V2 ÷ C1 · diluent = V2 − V1 · dilution factor = C1 ÷ C2
The dilution equation C1V1 = C2V2 states that the amount of solute is conserved when you dilute: concentration times volume before equals concentration times volume after. Solving for V1 tells you how much concentrated stock to draw, and the rest of the final volume is diluent. The dilution factor C1/C2 expresses the same result as a fold change, and as the familiar 1:X mixing ratio.
Worked example
To make 50 mL of a 10-unit solution from a 100-unit stock: V1 = (10 × 50) ÷ 100 = 5 mL of stock, topped up with 45 mL of diluent. The dilution factor is 100 ÷ 10 = 10×, i.e. a 1:10 dilution.
Sources: Dilution (equation) — Wikipedia
Frequently asked questions
Does the ratio mean part-to-part or part-to-total?
This tool reports the dilution factor as 1:X where X is the fold change (stock ÷ final). A 1:10 dilution means the final solution is one-tenth as concentrated — 1 part stock brought up to a total of 10 parts.
What units should I use?
Any consistent concentration units for C1 and C2 (mg/mL, molarity, X-fold), since they cancel. The stock and diluent volumes come out in whatever unit you use for the final volume.
Can I concentrate a solution with this?
No — C1V1 = C2V2 only dilutes. The final concentration cannot exceed the stock, so the tool requires C2 ≤ C1. Concentrating requires evaporation or a spin column, not mixing.
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Educational estimate, not medical or laboratory advice — verify formulas, units and assumptions for your specific protocol.