Antibody Dilution Series Calculator
Serial dilutions are used throughout immunology, biochemistry, and microbiology to prepare a range of concentrations from a single stock solution. This calculator generates a complete dilution series table showing the concentration at each step, the volume to transfer, and the volume of diluent to add. Enter your starting concentration, dilution factor, final volume per well, and number of steps needed. Results are suitable for planning ELISA, western blot, and flow cytometry antibody titrations.
| Step | Concentration | Transfer volume (mL) | Diluent volume (mL) |
|---|
Serial dilution formula
C(n) = C(0) / (dilution factor)^n
Transfer volume = final volume / dilution factor
Diluent volume = final volume - transfer volume
Where C(n) is the concentration at step n, C(0) is the starting concentration, and the dilution factor is the ratio by which the concentration decreases at each step.
Common antibody dilution series
- ELISA primary antibody titration: start at 1:500 to 1:2000, use 1:2 serial dilution, 8 to 10 steps.
- Flow cytometry: start at 1:20 to 1:200, use 1:2 or 1:3 series, 6 to 8 steps.
- Western blot: primary antibody typically 1:500 to 1:5000; titrate using 1:3 or 1:5 series.
- Serology (e.g. virus neutralisation): start at 1:10 serum dilution, use 1:2 series, 10 to 12 steps.
Antibody dilution series: frequently asked questions
What is a serial dilution?
A serial dilution is a stepwise dilution of a solution where each step reduces the concentration by the same factor (the dilution factor). For example, a 1:10 serial dilution starting at 1 mg/mL gives 0.1 mg/mL, then 0.01 mg/mL, and so on.
How do I calculate the concentration after n dilution steps?
Concentration after n steps = C(0) / (dilution factor ^ n). For a 1:5 dilution starting at 1,000 ng/mL, after 3 steps: 1,000 / (5^3) = 8 ng/mL.
What dilution factor should I use for antibody titration?
Common antibody titration dilution factors are 1:2, 1:3, 1:5, or 1:10 depending on the expected concentration range of your analyte. ELISA antibody titrations often use a 1:2 or 1:3 series starting at 1:100 to 1:1000.
How much volume do I need for each dilution step?
The volume transferred equals the final volume divided by the dilution factor. For a 1:10 dilution making 1 mL: transfer 0.1 mL of previous dilution into 0.9 mL diluent.
What is the difference between dilution ratio and dilution factor?
A 1:10 dilution ratio means 1 part sample in 10 parts total (sample + diluent = 9 parts diluent). The dilution factor is 10. A 1-in-10 dilution is equivalent to a 1:9 dilution (1 part sample added to 9 parts diluent).
Official sources
- NIH Biomedical Technology Resource Centers, antibody titration protocols: NCBI PubMed Central: Serial dilution method.
- CDC Laboratory Methods, serial dilution guide: CDC Laboratory Methods.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology.