Serial dilution calculator
Cₙ = C₀ ÷ fⁿ — one dilution factor repeated across bounded steps.
Any concentration unit — the whole table uses it.
1:10 series → f = 10.
1–20.
Diluent per step = transfer × (f − 1).
Enter the stock concentration, dilution factor, transfer volume, and step count — the final concentration and the full tube-by-tube table appear here.
Formula and how to use it
A serial dilution repeats one dilution factor f over n steps, so the concentration falls geometrically: Cn = C₀ ÷ fⁿ, where C₀ is the stock concentration. A 1:10 series has f = 10; after three steps the sample is diluted 1,000-fold, and after six steps, one million-fold.
Each step mixes a transfer volume Vt of the previous solution with diluent of Vt × (f − 1), giving a total volume of Vt × f. For a 1:10 dilution with a 100 µL transfer, add 900 µL of diluent for a 1,000 µL total; the new concentration is one tenth of the previous tube. The same factor at every step is what makes the series predictable.
This calculator builds the full step table — concentration, transfer volume, diluent volume, and total volume for each tube — for one to twenty steps. In practice a series usually stops before the last steps fall at or below the assay's detection limit, where pipetting error dominates the result.