Serial Dilution & Plating Factor Calculator
Designs multi-tube serial dilution protocols (1:2, 1:5, 1:10, etc.), tracking cumulative dilution factors, individual tube concentrations, transfer volumes, and colony-forming unit (CFU/mL) plating densities.
Multi-Tube Serial Dilution & Plating Factor Calculator
Design logarithmic multi-step serial dilution protocols and calculate microbiological colony-forming units (CFU/mL)
| Tube # | Step Factor | Cumulative TDF | Concentration |
|---|---|---|---|
| Tube 1 | 1 : 10 | 10^1 (1 : 10) | 1.000e-1 |
| Tube 2 | 1 : 10 | 10^2 (1 : 100) | 1.000e-2 |
| Tube 3 | 1 : 10 | 10^3 (1 : 1,000) | 1.000e-3 |
| Tube 4 | 1 : 10 | 10^4 (1 : 10,000) | 1.000e-4 |
| Tube 5 | 1 : 10 | 10^5 (1 : 100,000) | 1.000e-5 |
Microbiological Plating (CFU/mL)
What is a Serial Dilution?
A serial dilution is the stepwise dilution of a substance in solution, where the dilution factor is kept constant at each successive step.
It is widely used in microbiology, pharmacology, and molecular biology to reduce high bacterial concentrations or antibody titers to quantifiable, discrete colonies.
Formula & Step-by-Step Calculation
Step dilution factor, cumulative total dilution factor, and microbiological plating titer calculation.
Worked Step-by-Step Examples
10-fold serial dilution (1 mL into 9 mL diluent) across 5 tubes starting at 1.0 M. Tube 4 plated (0.1 mL) yielding 65 colonies.
Common Real-World & Academic Use Cases
- ✓ Microbiology bacterial viable plate counts (CFU/mL)
- ✓ ELISA antibody and viral plaque titer serial assays
- ✓ Minimum inhibitory concentration (MIC) antimicrobial testing
- ✓ Analytical standard curve calibration serial preparation
How to Use the Serial Dilution & Plating Factor Calculator
Set Initial Stock & Steps
Enter initial stock concentration, number of dilution tubes (e.g. 5 to 10), and transfer volume.
Choose Dilution Factor
Select 1:10 (tenfold), 1:2 (twofold), 1:5, or custom diluent volume per tube.
Inspect Tube Table & CFU Plating
Review step-by-step pipetting guide, cumulative dilution factor for each tube, and enter colony counts to compute CFU/mL.
Frequently Asked Questions
Q: What is an acceptable colony count range for plate counts?
By standard microbiological convention, agar plates with between 30 and 300 colonies are statistically valid for calculating CFU/mL (avoiding overcrowding or statistical noise).