This calculator finds the concentration remaining after a repeated serial dilution. Enter the starting concentration, the dilution factor used at each step, and the number of dilution steps; the page applies the same factor repeatedly and reports the final concentration together with the total fold dilution.
It is useful when planning assay standards, microbiology plates, calibration series, or any workflow in which each tube is prepared from the previous tube. The model assumes the same dilution factor at every step, so it is best for regular serial-dilution schemes rather than mixed-ratio sequences.
1. Enter the starting concentration
Use any concentration unit as long as you keep that same unit when reading the result.
2. Set the per-step dilution factor
For a 1:10 dilution at every transfer, enter 10. The factor must be greater than 1.
3. Enter the number of transfers
Count only the dilution steps that are actually performed.
4. Review the final concentration
The main result is the concentration after the last step; the breakdown also shows the cumulative dilution.
Final concentration = Starting concentration ÷ (Dilution factor ^ Number of steps)The cumulative dilution factor is the per-step factor raised to the number of steps. This model assumes an identical dilution ratio at every transfer and complete mixing before the next transfer.
The result is the expected concentration in the final tube or well, expressed in the same concentration unit used for the starting value.
Real laboratory results can differ because of pipetting tolerance, mixing, adsorption, evaporation, or measurement error.
Given: starting concentration = 240 µg/mL, dilution factor = 4, steps = 3.
Calculation: Total dilution = 4³ = 64. Final concentration = 240 ÷ 64 = 3.75 µg/mL.
Result: The third diluted sample is expected to contain 3.75 µg/mL, or 1.5625% of the starting concentration.
It means each step reduces the concentration to one tenth of the previous step. Repeating that step three times produces a total 1,000-fold dilution.
Yes. The formula is unit-neutral, so the output uses the same concentration unit as the starting input.
This page assumes one constant factor. For mixed ratios, calculate each step separately or multiply the individual dilution factors first.
A factor of 1 would not dilute the sample, while a value below 1 would mathematically increase concentration rather than represent a dilution.
No. It is an ideal volume-and-concentration calculation and does not model pipette bias, dead volume, or incomplete recovery.