Dilution Factor Calculator
Work out the dilution factor from your sample and diluent volumes, and the final concentration after diluting a stock solution.
How it works
Dilution factor = (sample + diluent) ÷ sample · Final concentration = stock ÷ dilution factor
A dilution factor tells you how many times a solution has been diluted. It is the total volume after mixing divided by the volume of sample you started with, usually written as 1:X. Because concentration falls in exact proportion to that factor, dividing the stock concentration by the dilution factor gives the final concentration. A one-part-sample-to-nine-parts-diluent mix is the common tenfold (1:10) dilution.
Worked example
Adding 1 part sample to 9 parts diluent gives a total of 10 parts, so the dilution factor is 10 ÷ 1 = 10, written 1:10. A 100-unit stock diluted 1:10 becomes 100 ÷ 10 = 10 units.
Sources: Serial dilution — Wikipedia
Frequently asked questions
How is dilution factor written?
Usually as a ratio like 1:10, meaning one part of the original in ten parts total. Numerically it is the total volume divided by the sample volume, so 1 mL of sample in 9 mL of diluent is a factor of 10, or 1:10.
What is the difference between diluent and total volume?
The diluent is only the liquid you add; the total (final) volume is the sample plus the diluent. The dilution factor uses the total volume over the sample volume, so a 1:10 dilution has 9 parts diluent added to 1 part sample.
How do serial dilutions compound?
Each step multiplies the previous factor. Three consecutive 1:10 dilutions give an overall factor of 10 × 10 × 10 = 1,000 (1:1000), which is how labs reach very low concentrations in manageable steps.
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Educational estimate, not medical advice — verify formulas, units and assumptions for your specific case.