How It Works
This comparator works in 4 steps.
Enter the total dilution
Type the overall DF.
Enter the final volume
Type the working volume needed.
Enter pipette accuracy
Type the relative error at small and large volumes, such as 5% at 1 µL and 1% at 100 µL.
Compare routes
The tool lists transfer volume, diluent use, tips, and combined error for the direct and serial routes.
The Formula
The formula computes the direct transfer volume and the serial stage transfer, then combines stage errors by root-sum-square.
V_direct = V_final / DFV_stage = V_final / DF^(1/n)u_serial = √n × u_stage- DF:
- Total dilution factor
- n:
- Number of serial stages
- u_stage:
- Relative error of one stage
- u_serial:
- Combined relative error
A 1:10,000 dilution to 1 mL needs a 0.1 µL direct transfer. Two 1:100 stages need 10 µL each. At 1.5% error per 10 µL stage, the serial route carries √2 × 1.5% = 2.1% error.
Conversion Table
The conversion table compares direct transfers with pipette-friendly serial plans for 5 dilutions.
| Total DF | Final volume | Direct transfer | Serial plan | Serial transfer | Stages |
|---|---|---|---|---|---|
| 100 | 1 mL | 10 µL | 1 × 1:100 | 10 µL | 1 |
| 1,000 | 1 mL | 1 µL | 1:10 then 1:100 | 100 µL, then 10 µL | 2 |
| 10,000 | 1 mL | 0.1 µL | 2 × 1:100 | 10 µL | 2 |
| 10⁶ | 1 mL | 0.001 µL | 3 × 1:100 | 10 µL | 3 |
| 1,000 | 10 mL | 10 µL | 1:10 then 1:100 | 1 mL, then 100 µL | 2 |
What Is the Direct vs Serial Dilution Comparator?
The Direct vs Serial Dilution Comparator is a tool that compares one direct dilution with a serial plan for the same target and reports transfer volumes, diluent use, tip count, and expected error for each route. The comparison shows which route keeps the transfer volume above the pipette's accurate range.
Direct dilution has 1 transfer and 1 source of error. Serial dilution has several transfers, so error compounds, but each transfer is larger and more accurate. The comparator puts both routes side by side with the user's pipette accuracy values, so the choice rests on numbers.
Common Uses
There are 5 main uses of this comparator.
Method selection
Analysts pick the route with the lower combined error.
SOP justification
Method writers record why a serial route replaces a direct route.
Error budgets
Metrologists include dilution route error in measurement uncertainty.
Reagent savings
Users compare diluent use between 1 large flask and several small tubes.
Training
Trainers show the trade-off between transfer size and error compounding.