How do you calculate the overall serial dilution factor?
Short answer
Calculate each step’s dilution factor as final volume divided by transferred stock volume, then multiply the step factors. Transferring 1 milliliter into 9 milliliters of diluent gives a factor of 10 under additive volumes. Two such steps followed by a fivefold step give an overall factor of 500. Final concentration equals original concentration divided by that overall factor.
A starting concentration of 100 becomes 10, then 1, then 0.2 after factors of 10, 10, and 5. Keep the concentration unit consistent throughout.
What changes when an earlier dilution step changes?
Every downstream starting concentration must change too. In an independently entered step table, update the next row’s starting concentration or link it explicitly to the previous row’s result.