Design dilution series with clear volumes and ratios. Check final concentration and overall factor instantly. Export a clean report, then repeat your protocol safely.
| Scenario | Inputs | Expected outcome (summary) |
|---|---|---|
| Typical 10-fold series | C0 = 1.0e8 CFU/mL, Steps = 6, Ratio = 1:10, Final volume = 1000 µL | Overall DF = 1,000,000, Final concentration = 1.0e2 CFU/mL, Transfer per step ≈ 100 µL |
| Mixed series | C0 = 5.0e6 ng/µL, Custom list = 10, 10, 100, Final volume = 500 µL | Overall DF = 10,000, Final concentration = 5.0e2 ng/µL, Step volumes adapt by factor |
Use the example values to validate your workflow, then swap in your lab’s actual volumes and ratios.
Serial dilution converts a dense sample into measurable ranges. A 10-fold series turns 1.0×108 cells/mL into 1.0×102 cells/mL after six steps. That span helps plating, qPCR standards, enzyme assays, and microscopy counts. The calculator keeps each step explicit, so you can reproduce the same series across days and operators. Many labs run duplicates to estimate variance and keep mixing consistent: five inversions or 10 seconds vortexing per tube reduces gradients and carryover between steps.
For one step, the dilution factor is DF = Vfinal/Vtransfer. A “1:10” step means one part sample in ten parts total, so DF = 10 and the dilution fraction is 0.1. The overall factor multiplies across steps: DFtotal = ΠDFi. Concentration after n steps is Cn = C0/DFtotal.
Pipettes are least reliable near their minimum range. If your step requires 10 µL transfers, random error can rise sharply and drift compounds over steps. Using 100 µL into 900 µL (final 1000 µL) keeps transfers comfortable and yields DF = 10. The tool also reports diluent volume, supporting consistent tube preparation and mixing.
Plate counts are commonly interpreted in the 30–300 colony range. Suppose you expect 1.0×108 CFU/mL and plate 0.1 mL. A 10−6 total dilution predicts about 10 colonies, while 10−5 predicts about 100 colonies. Testing adjacent dilutions is practical insurance when growth varies or clumping occurs.
Recorded dilution tables reduce transcription mistakes. CSV export fits lab notebooks, LIMS uploads, and spreadsheet checks. PDF export creates a clean attachment for protocols, training, or audits. Include method, volumes, and step count so another user can rebuild the same dilution tree without guessing the intended ratios.
Confirm units match your assay (mL versus µL). Verify that final volume exceeds transfer volume for real dilution. Scan the plot: concentrations should decrease monotonically and by the expected step ratio. If one step looks off, recheck the entered factor, mixing practice, and tube labeling before consuming reagents.
A ratio describes parts mixed (sample:total). The dilution factor is the numeric reduction, usually total ÷ sample. For 1:10, DF = 10 and concentration becomes one tenth each step.
When you enter a value below 1 in the custom list, the calculator treats it as a dilution fraction. So 0.01 is interpreted as 1/0.01, giving a step factor of 100.
A dilution needs added diluent. If transfer volume equals or exceeds final volume, there is no true dilution and the computed factor becomes 1 or less, which breaks serial planning.
Estimate expected density and plated volume, then choose steps that land near 30–300 colonies. In practice, 5–8 steps of 10-fold dilution often brackets the countable range.
Yes. Use the custom list and enter step factors or ratios for each tube. The overall factor is the product of all step factors, and the table shows each cumulative value.
Keep volumes in the same unit within a run. The unit selector labels the table. If you switch from µL to mL, convert values before entering so transfer and diluent volumes stay consistent.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.