⚗️ Lab Calculators
Serial Dilution Calculator
Calculate the concentration at every step of a serial dilution series. Set your stock concentration, dilution factor, number of steps and volume — get a complete table instantly.
How to Use the Serial Dilution Calculator
Enter your starting (stock) concentration, select a dilution factor, choose the number of steps, and optionally enter a volume per tube. Click Calculate Series to generate a complete dilution table showing the concentration and notation at each step.
If a volume is entered, the table also shows the transfer volume (how much to take from the previous tube) and the diluent volume (how much solvent to add) for each step.
Serial Dilution Formula
Cn = C0 ÷ DF^n | Transfer Vol. = Total Vol. ÷ DF
Cn = concentration at step n | C0 = stock concentration | DF = dilution factor | n = step number
Common Applications
Microbiology — Plate Counts
10-fold serial dilutions of bacterial cultures (CFU/mL) before plating on agar for colony counting and viable cell counts.
ELISA Standard Curves
2-fold serial dilutions of antibody or antigen standards to generate a dose-response curve for quantification.
Drug / Inhibitor Studies
2-fold or 3-fold serial dilutions of drugs in cell culture to determine IC50 or MIC values.
Western Blot Antibodies
2-fold serial dilutions of primary or secondary antibodies to optimise signal-to-noise ratio for blotting.
About Serial Dilutions
A serial dilution is a stepwise sequence of dilutions where each step uses the same dilution factor. It is the standard method to prepare a wide range of concentrations from a single stock solution without performing individual dilutions from scratch each time.
The most common serial dilutions in microbiology are 10-fold (1:10) dilutions, where 1 part sample is mixed with 9 parts diluent at each step. In immunology and biochemistry, 2-fold dilutions are common for titration assays and standard curve preparation.
Reading Dilution Notation
1:10 dilution
1 part sample + 9 parts diluent = 10 parts total. Concentration is 1/10th of the previous step. Also written as 10⁻¹.
1:100 dilution
After two 1:10 steps. Concentration is 1/100th of stock. Also written as 10⁻².
1:2 dilution
1 part sample + 1 part diluent. Used in immunology for antibody titrations and ELISA standard curves.
Cumulative factor
After n steps with factor DF, the cumulative dilution = DF^n. After 6 × 10-fold steps: dilution = 10⁶ = 1,000,000-fold.
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