Serial Dilution Calculator
Use this serial dilution calculator to build a step-by-step fold-dilution series. Enter your stock concentration, the fold per step (e.g. 10 for a tenfold series), the number of steps and the volume per tube — the table below gives the cumulative dilution factor and resulting concentration for every step, plus the transfer and diluent volumes to pipette.
Fill in all four fields to build the dilution series and see the per-tube transfer volumes.
How serial dilution works
In a serial dilution you dilute a solution by a fixed fold factor, then use that diluted solution as the starting point for the next dilution, and repeat. Because each step multiplies the previous dilution, the concentration drops geometrically and a handful of steps can cover several orders of magnitude using only small, accurate volumes.
The cumulative dilution after a number of steps is the fold factor raised to the number of steps, so the total dilution = fold^steps. The concentration at any step is the stock divided by that cumulative factor:
Transfer and diluent volumes
For an n-fold dilution in tubes of a fixed total volume, you transfer (total ÷ fold) of the previous tube and make up the rest with fresh diluent. A 10-fold step in 1 mL tubes therefore means transferring 0.1 mL into 0.9 mL of diluent, mixing, then carrying 0.1 mL forward to the next tube.
Worked example
Start with a 1 M stock and run a 10-fold series of 5 steps. The concentrations become 0.1 M, 0.01 M, 0.001 M, 0.0001 M and 0.00001 M (1:10, 1:100, 1:1000, 1:10,000 and 1:100,000). For 1 mL tubes you transfer 0.1 mL of the previous solution into 0.9 mL of diluent at each step.
Related tools
If you only need a single dilution from a ratio like 1:10, the dilution ratio calculator turns it into exact stock and solvent volumes. To solve C₁V₁ = C₂V₂ for a specific target concentration instead, use the dilution calculator.
Frequently asked questions
›What is a serial dilution?
A serial dilution is a sequence of step-by-step dilutions, where the diluted solution from one tube becomes the stock for the next. Each step reduces the concentration by the same fold factor, so after a few steps you can span several orders of magnitude with small, easy-to-measure volumes. It is the standard way to build calibration curves and to plate countable numbers of cells or colonies.
›How do you calculate a serial dilution?
The concentration after step n is the stock concentration divided by the fold factor raised to the power n: concentration = stock ÷ foldⁿ. The cumulative dilution factor at step n is simply foldⁿ. For the volumes, an n-fold step transfers (total volume ÷ fold) of the previous tube into the rest of the tube filled with diluent — for a 10-fold series in 1 mL tubes, transfer 0.1 mL into 0.9 mL of diluent. This calculator does all of that for you.
›What does a 10-fold serial dilution mean?
A 10-fold (or tenfold) serial dilution reduces the concentration by a factor of 10 at every step. Tube 1 is 1:10, tube 2 is 1:100, tube 3 is 1:1000, and so on, so the total dilution is 10 raised to the number of steps. In practice you transfer 1 part of the previous solution into 9 parts of fresh diluent at each step.
›Is this serial dilution calculator free?
Yes. This serial dilution calculator is completely free, runs entirely in your browser, needs no sign-up, and never sends your numbers to a server.
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