Serial Dilution Calculator
Compute per-step and cumulative dilution factors, final concentration, and a tube-by-tube concentration table.
Enter the starting concentration of your sample.
Per-step dilution factor
10
Total dilution factor
100,000
Final concentration
0 mg/mL
Each tube volume: 10 mL (aliquot + diluent).
Dilution Table
| Step | Tube | Cumulative factor | Concentration (mg/mL) |
|---|---|---|---|
| 1 | Tube 1 | 10 | 0.1 mg/mL |
| 2 | Tube 2 | 100 | 0.01 mg/mL |
| 3 | Tube 3 | 1,000 | 0.001 mg/mL |
| 4 | Tube 4 | 10,000 | 0.0001 mg/mL |
| 5 | Tube 5 | 100,000 | 0 mg/mL |
How to Use This Calculator
Measure aliquot and diluent volumes
Decide how much sample and diluent you will use for each dilution step.
Enter starting concentration
Provide the initial sample concentration and specify the units for clarity.
Set the number of steps
The calculator applies the same dilution factor for each step and generates a complete table.
Review dilution table
Use the per-tube concentrations to plan assays, plating, or analytical measurements.
Formula
Dilution factor per step = (Vᵢ + V_d) / Vᵢ
Cₙ = C₀ / (factor)ⁿ
Vᵢ is the aliquot volume transferred each step, V_d is diluent volume, and n is the step number. C₀ is starting concentration.
Example
Using 1 mL aliquot + 9 mL diluent (factor = 10) for 4 steps gives concentrations C₀/10, C₀/100, C₀/1000, C₀/10000.
Full Description
Serial dilutions reduce concentration stepwise, often by the same factor, enabling measurement of analytes across wide dynamic ranges. This calculator automates the repetitive math and produces a dilution schedule for lab execution.
Use it for microbiology plating, ELISA standards, spectrophotometry, or any workflow requiring controlled successive dilutions.
Frequently Asked Questions
Do I need to discard volume between steps?
Yes. After mixing, remove the aliquot for the next tube. Residual volume remains in the previous tube.
Can steps have different factors?
This calculator assumes identical steps. For varied factors, compute each manually or run separate calculations.
How accurate are dilutions?
Accuracy depends on pipetting technique. Use calibrated pipettes and mix thoroughly at each step.
How do I convert concentrations to counts?
Use the final concentration to interpret assay results (e.g., multiply colony counts by dilution factor).
Can I copy the table?
Yes. Copy and paste the table into lab protocols or worksheets for quick reference.