Serial Dilution Calculator
Calculate serial dilution steps, volumes, and concentrations for laboratory experiments
Calculate Serial Dilution
Total number of solutions to prepare (2-20)
Factor by which each dilution reduces concentration
Concentration of the first solution in series
Concentration of original stock solution
Volume Requirements
Serial Dilution Results
Dilution Factor
Volume to Transfer
Minimum Volume
Total Dilutant
Starting Solution Composition
Starting Volume Needed
Stock Solution Required
Dilutant to Add
Dilution Steps
| Step | Concentration | Volume Transfer | Dilutant Add | Total Volume | Dilution Factor |
|---|---|---|---|---|---|
| 1 | 1.00e+2 M | — | — | 3.30 mL | 1:1.0 |
| 2 | 1.00e+1 M | 0.37 mL | 3.30 mL | 3.67 mL | 1:10.0 |
| 3 | 1.00e+0 M | 0.37 mL | 3.30 mL | 3.67 mL | 1:100.0 |
| 4 | 1.00e-1 M | 0.37 mL | 3.30 mL | 3.67 mL | 1:1000.0 |
| 5 | 1.00e-2 M | 0.37 mL | 3.30 mL | 3.67 mL | 1:10000.0 |
Formulas Used
Dilution Factor (concentration range): fd = (cinitial ÷ cfinal)^(1/(nd-1))
Volume to Transfer: Minimum Volume ÷ (Dilution Factor - 1)
Stock Volume Required: (Starting Volume × Starting Concentration) ÷ Stock Concentration
Final Concentration: Starting Concentration ÷ (Dilution Factor)^step
Minimum Volume: Volume per Use × Number of Uses + Error
Example Calculation
Bacterial Culture Dilution Example
Goal: Create 6 dilutions for colony counting
Starting concentration: 10^6 CFU/mL
Dilution factor: 1:10 (10-fold dilutions)
Volume needed: 1 mL per dilution, 3 uses each
Error allowance: 10% extra volume
Step-by-Step Solution
1. Minimum volume = 1 mL × 3 uses + 10% = 3.3 mL
2. Volume to transfer = 3.3 mL ÷ (10 - 1) = 0.367 mL
3. Starting volume = 3.3 mL + 0.367 mL = 3.667 mL
4. Each dilution: Transfer 0.367 mL + add 3.3 mL dilutant
5. Final concentrations: 10^6, 10^5, 10^4, 10^3, 10^2, 10^1 CFU/mL
Result: 6 precise 10-fold serial dilutions ready for plating
Common Dilution Series
1:10 Dilution Series
Factor: 1:10, Start: 100 mg/mL
1:2 Dilution Series
Factor: 1:2, Start: 1000 μM
1:5 Dilution Series
Factor: 1:5, Start: 50 mM
Bacterial Culture
Factor: 1:10, Start: 1000000 CFU/mL
Protein Assay
Factor: 1:4, Start: 10 mg/mL
Drug Testing
Factor: 1:3, Start: 1000 μg/mL
Dilution Tips
Use fresh pipette tips for each dilution
Mix thoroughly but gently to avoid bubbles
Label tubes clearly before starting
Work from highest to lowest concentration
Include extra volume for pipetting errors
Understanding Serial Dilutions
What is a Serial Dilution?
A serial dilution is a stepwise dilution of a solution where the concentration decreases with each step by a constant factor. It's commonly used in chemistry, biology, and medicine to create a range of concentrations from a stock solution.
Applications
- •Bacterial and cell culture quantification
- •Drug concentration testing
- •Protein and enzyme assays
- •Antibody titrations
- •UV-Vis spectrometry sample preparation
Key Formulas
fd = (Cinitial ÷ Cfinal)^(1/(n-1))
Vtransfer = Vmin ÷ (fd - 1)
Cfinal = Cinitial ÷ (fd)^step
Calculation Methods
- Dilution Factor: Specify the constant ratio between dilutions
- Concentration Range: Define start and end concentrations
- Volume Planning: Account for experimental needs and errors
Pro Tip: Always prepare extra volume to account for pipetting errors and multiple uses.
Serial Dilution Procedure
Step-by-Step Protocol
Prepare Starting Solution
Mix stock solution with dilutant to reach starting concentration
Label Tubes
Clearly mark each tube with dilution step and expected concentration
Add Dilutant
Add calculated dilutant volume to each empty tube
Serial Transfer
Transfer calculated volume from one tube to the next, mix well
Verification
Check final volumes and verify concentration calculations
Common Mistakes to Avoid
Cross-contamination
Use fresh pipette tips between dilutions
Insufficient mixing
Mix thoroughly but avoid creating bubbles
Volume errors
Double-check pipette calibration and settings
Temperature effects
Keep solutions at consistent temperature
Best Practices
- • Work in order from highest to lowest concentration
- • Prepare 10-20% extra volume for safety
- • Use appropriate pipette size for accuracy
- • Record actual volumes used for traceability
- • Store dilutions properly if not used immediately