Serial Dilution Calculator

Calculate serial dilutions for laboratory experiments. Enter the initial concentration, dilution factor, and number of steps to see the complete dilution series with concentrations.

Starting concentration

How much to dilute each step (e.g., 10 for 1:10)

Number of serial dilution steps

Volume transferred each step

Volume in each tube after dilution

Serial Dilution Formulas: Total Dilution: Total DF = (Dilution Factor)^(Number of steps) Concentration Calculation: C_final = C_initial / Total DF Concentration at each tube: C_n = C_initial / (DF)^n Dilution Ratio: For DF = X: Transfer X-1 parts into X parts diluent For 10-fold: 1 part + 9 parts diluent For 2-fold: 1 part + 1 part diluent Volume Calculation: Solvent Volume = Total - Transfer Example: Want 1 mL, transfer 100 µL → add 900 µL solvent
Example 1 (10-fold serial dilution): Initial: 100 mM Dilution factor: 10 Number of dilutions: 5 Total dilution: 10^5 = 100,000 Final: 100 mM / 100,000 = 1 µM Series: 100 → 10 → 1 → 0.1 → 0.01 → 0.001 mM Example 2 (2-fold dilution): Initial: 10 µM Dilution factor: 2 Number: 8 dilutions Total: 2^8 = 256-fold Final: 10/256 = 0.039 µM = 39 nM Series: 10 → 5 → 2.5 → 1.25 → 0.625... µM Example 3 (Practical volumes): Transfer 100 µL into 900 µL diluent Performs a 1:10 dilution After 5 transfers, 100 µL total moved Remaining in each tube = 900 µL solvent + small amount Example 4 (Complete series): Starting: 1 M stock 1:10 dilution, 6 tubes Concentrations: 1M → 0.1M → 10mM → 1mM → 100µM → 10µM → 1µM

What is a serial dilution?

A serial dilution is a stepwise dilution where each step uses the previous dilution as the starting material. For example, a 1:10 dilution repeated 5 times creates a 10⁻⁵ dilution overall. This method is standard in microbiology, biochemistry, and pharmacology for creating concentration series.

How do I calculate total dilution?

Total dilution = (Dilution Factor)^(Number of dilutions). For a 1:10 dilution repeated 4 times: Total = 10^4 = 10,000-fold. If starting at 100 mM, final concentration = 100 mM / 10,000 = 0.01 mM = 10 µM. Each tube is 10x more dilute than the previous.

How much transfer and diluent do I need?

For a 1:10 dilution (DF=10): If you want 1 mL final volume, use 100 µL stock + 900 µL diluent, or transfer 100 µL into 900 µL. The ratio is Transfer : (Total - Transfer). For 1:2, transfer 500 µL into 500 µL. Adjust volumes based on your needs.

What is a dilution factor?

Dilution factor (DF) is how many times the concentration decreases at each step. A 1:10 dilution has DF = 10. A 1:2 dilution has DF = 2. Total dilution = DF^steps. The term "fold" also means the same - a 10-fold dilution is a 1:10 dilution (10 mL into 90 mL or 1 mL into 9 mL).

What are serial dilutions used for?

Serial dilutions are used for: MIC (minimum inhibitory concentration) testing in microbiology, ELISA standard curves, drug IC50 determination, creating calibration standards, determining enzyme kinetics (Km, Vmax), and any experiment requiring multiple concentrations.

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