Serial dilution

Plan a dilution series or dilute one sample. Enter starting concentration C₀, transferred sample volume and diluent volume. Each quantity uses its selected unit. A series has 1–100 steps.

At each step D = (Vₜ + Vᵈ) / Vₜ and Cₙ = C₀ / Dⁿ. For example, 10 µL sample plus 90 µL diluent gives factor 10, not 0.1. Mix thoroughly before transferring onward; each new tube contains fresh diluent.

Each intermediate tube retains Vᵈ after transfer. The final tube normally retains Vₜ + Vᵈ. “Equal remaining volumes” discards one transfer volume from the final tube, leaving Vᵈ in every tube without changing concentration.

In Target series, enter the last concentration and the volume to retain in each tube. The calculator finds a constant dilution factor and the transfer per step. Add the specified retained volume as fresh diluent to each tube. After mixing the last tube, discard one transfer volume to leave the same amount in every tube.

This plan assumes additive volumes. It does not predict ELISA signals or calibration curves, reactions, adsorption, evaporation or pipetting errors. Use the Dilution tool when filling to an exact final volume.

Concentration units convert within each family. Molar and mass inputs are kept separately. CSV gives unrounded volumes, concentrations and log₁₀ of the cumulative dilution factor. Results update as you type. Reset restores the example.

Basis: OpenStax Chemistry 2e, 3.3.