Chemistry · Lab planning
Serial dilution calculator.
Plan a series with a constant dilution factor: what to transfer, what diluent to add, and the concentration at every step.
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How a serial dilution works
A serial dilution is a step-by-step dilution with a constant dilution factor, so the concentration falls in a geometric progression. A ten-fold series from 1 M goes 0.1 M, 0.01 M, 0.001 M, and so on. Each tube is made by transferring a small volume of the previous tube into fresh diluent: transfer volume = final volume / dilution factor, diluent = final volume - transfer, and the concentration of tube k is stock / factork.
Worked example. Stock 1, ten-fold, 6 steps, 1 mL per tube. Transfer 1 / 10 = 0.1 mL and add 0.9 mL of diluent each time. The six tubes read 0.1, 0.01, 0.001, 1.00 x 10^-4, 1.00 x 10^-5, 1.00 x 10^-6, a total dilution of 1,000,000 x.
Mix each tube well and change the pipette tip between transfers. Each tube except the last loses the transfer volume to the next one, so prepare a little extra if you need the full volume afterwards.
Frequently asked questions
What is a serial dilution?
A series of dilutions, each made from the previous one, using the same dilution factor each time. It reaches very low concentrations accurately without measuring tiny volumes.
How do I set up a 1:10 series?
Put 9 parts diluent in each tube, transfer 1 part from the previous tube and mix. For a 1 mL tube that is 0.9 mL diluent and 0.1 mL transfer.
What is the difference between 1:10 and 10-fold?
Notations vary. "1:10" is often used for 1 part in 10 total (factor 10), but some labs mean 1 part plus 10 parts (factor 11). Enter the real factor you use.
How do I get the concentration after n steps?
Divide the stock concentration by the dilution factor raised to the power n.
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Lab safety and scope
This is arithmetic, not professional advice. Check every result against your own procedure, the safety data sheet (SDS) for each chemical, and your lab supervisor or instructor before you prepare, mix or dispose of anything. Verify values on the reagent bottle, since purity and hydration state change the real molar mass.