Serial Dilution Calculator
Plan fixed-fold and custom serial dilution series for laboratory workflows. This serial dilution calculator helps scientists prepare dilution series for antibody dilutions, standard curves, dose-response assays, qPCR standards, microbial plating, viral workflows, and routine reagent preparation with practical pipetting checks and bench-ready instructions.
Dilution Setup
Choose a fixed-fold serial dilution or enter custom target concentrations. Use compatible concentration units so the calculator can convert units safely.
Fixed-Fold Series Setup
Custom Target Concentration Setup
Target concentrations
Practical Bench Settings
Serial Dilution Results
Bench Setup Summary
Dilution Instructions Table
Bench Protocol
Concentration Graph
Detailed calculations
Lab Summary Card
Formula and Calculation Logic
Fixed-Fold Serial Dilution
A fixed-fold serial dilution applies the same dilution factor at each step. For example, a 2-fold serial dilution halves the concentration at every step, while a 10-fold serial dilution reduces each step by a factor of ten.
- Cn
- concentration at dilution step n
- C0
- starting concentration
- F
- dilution factor
- n
- dilution step number
Custom Target Dilution
Custom target dilutions use the selected source concentration and final volume to calculate the transfer volume needed for each target concentration. Compatible concentration units should be converted before the calculation.
- C1
- source concentration
- V1
- transfer volume from source
- C2
- target concentration
- V2
- final volume
Calculations assume compatible concentration units, additive volumes, accurate pipetting, and complete mixing after each dilution.
Example Workflow
A scientist is preparing an eight-point 1:2 serial dilution of an antibody for an ELISA experiment. Each dilution must provide enough volume for triplicate wells plus a 10% preparation overage while keeping all transfer volumes above the laboratory's minimum reliable pipetting volume.
Select fixed-fold serial dilution, choose 1:2, enter eight dilution steps, and enter the starting antibody concentration.
Enter the final volume per dilution and practical bench settings so the dilution series calculator can check replicate volume and overage needs.
Review the bench summary, warnings, and table before labeling tubes, adding diluent, transferring sample, and mixing each dilution thoroughly.
Common Mistakes
Preparing a dilution from the wrong tube changes every concentration that follows. Verify the correct source before every transfer.
Incomplete mixing produces inaccurate concentrations. Mix each dilution thoroughly before removing liquid for the next step.
Using the same pipette tip between dilution steps can carry concentrated sample into later tubes. Change tips between transfers.
Calculate enough volume for all planned replicates plus extra overage to account for normal pipetting losses.
Very small transfer volumes increase experimental variability. Increase preparation volume or create an intermediate dilution when practical.
Only calculate dilutions using compatible concentration units. Mixing unrelated unit families produces incorrect results.
Frequently Asked Questions
What is a serial dilution?
A serial dilution is a sequence of repeated dilutions in which each tube becomes the source for the next, producing predictable concentration changes across the series.
How do you calculate a serial dilution?
Fixed-fold serial dilutions repeatedly apply the same dilution factor, while custom target concentrations use C1V1 = C2V2. This serial dilutions calculator performs the calculations and generates bench-ready instructions.
What is a 2-fold serial dilution?
A 2-fold serial dilution halves the concentration at every step, producing concentrations such as 1, 1/2, 1/4, 1/8, and 1/16 of the starting concentration.
Should I prepare each dilution from the stock or the previous tube?
Preparing from stock minimizes cumulative error but may require impractically small transfer volumes. Preparing from the previous dilution often improves transfer volume but compounds pipetting and mixing error across the series.
Why does the calculator recommend an intermediate dilution?
Intermediate dilutions improve pipetting accuracy when direct transfers from stock would require volumes below your laboratory's practical pipetting limit.
Should I change pipette tips between dilution steps?
Yes. Changing pipette tips between transfers minimizes carryover contamination and helps preserve the intended concentration of each dilution.