🧪Serial Dilution Calculator
Plan a dilution series, solve for the required factor, or back-calculate CFU/mL from plated colonies.
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Free Serial Dilution Calculator
Setting up a dilution series for lab work? Our free serial dilution calculator does the math for you. Enter your starting concentration, dilution factor, and number of steps, and get a full table showing exactly how much stock and diluent to use at every tube — plus the resulting concentration after each step.
Need equal log-steps to hit a specific target concentration? Switch to solve-for-factor mode and the calculator works out the right dilution factor automatically. Microbiology users get a dedicated CFU/mL mode: enter your plated colony count, dilution factor, and volume plated, and back-calculate the original bacterial concentration instantly.
A simple visual diagram shows the full dilution chain so you can double-check your setup before you're at the bench. No sign-up, no downloads — just accurate dilution math whenever you need it. See the About page or the FAQ for more.
About the Serial Dilution Calculator
Features
Forward planning
Per-step and cumulative dilution factor, volumes, and concentration.
Solve-for-factor
Computes the equal per-step factor to hit a target concentration.
CFU/mL mode
Back-calculates original concentration from plated colony counts.
Visual diagram
A tube-by-tube diagram shows the full dilution chain.
Frequently Asked Questions
How does the serial dilution calculator work?
Enter your starting concentration, dilution factor, and number of steps, and it generates a full table of volumes and resulting concentrations for each dilution.
What is a dilution factor?
The ratio of total volume to stock volume in a dilution — e.g. a 1:10 dilution means 1 part stock plus 9 parts diluent for 10 total parts.
Can it work out the dilution factor for me?
Yes, give it your start and target concentration plus the number of steps, and it computes the required equal per-step factor.
What is the CFU/mL mode for?
It back-calculates original bacterial concentration from a plate count: colonies ÷ (dilution factor × volume plated).
What units can I use?
mol/L, mg/mL, CFU/mL, percentage, or a generic units/mL option — pick whichever matches your experiment.
What if my transfer volume is larger than the tube volume?
The calculator flags this as invalid, since you can't transfer more liquid than the tube holds.
Does it show a visual diagram of the dilution series?
Yes, a simple tube-by-tube diagram shows the full chain so you can verify your setup.
Can I export the dilution table?
Yes, copy it as plain text for your lab notebook or report.
Is this tool free?
Completely free, no sign-up or downloads.
Does it work on mobile?
Yes, fully responsive, with the table scrolling cleanly on small screens.