Serial Dilution Calculator

This calculator works out the concentration at each step of a serial dilution, the technique of repeatedly diluting a solution by a fixed factor to produce a range of precisely known, decreasing concentrations. Serial dilution is a cornerstone method in chemistry, biology and microbiology: by taking a small volume of a solution and diluting it by the same factor again and again, you create a series of concentrations spanning many orders of magnitude, which is exactly what is needed to build calibration curves, count cells or bacteria, or test a substance across a wide range. Each step multiplies the dilution, so a tenfold series quickly reaches very low concentrations from a strong stock. This calculator generates the whole series. You enter the starting stock concentration, the dilution factor applied at each step, and the number of steps, and the calculator returns the concentration after the final step, the dilution factor and step count for reference, the total dilution achieved, and the full list of concentrations at every step. The results update as you type. Use it for laboratory work, for planning a dilution series, or for chemistry and biology study. At each step the concentration is divided by the dilution factor, so after a number of steps the concentration is the stock divided by the factor raised to the power of the number of steps. A tenfold dilution factor, the most common, drops the concentration by an order of magnitude at every step, while the total dilution is the factor raised to the number of steps. Serial dilution is preferred over making each low concentration directly because it is far more accurate: measuring a small volume and diluting it repeatedly avoids the impracticality and error of trying to pipette a tiny amount of a very strong stock in one go. The calculator lists every intermediate concentration so you can label your tubes and know exactly what each contains.

Each step divides the concentration by the dilution factor. After n steps: concentration = stock / factor^n. Total dilution = factor^n. Lists every step below.