🧪Dilution Calculator

About this tool

Choose the unknown and enter the other three values, each in its own unit: M, mM, µM or nM for concentration, and L, mL or µL for volume. Switch to Other for percentages, mg/mL or ×-strength buffers. The calculator gives the volume of stock to use, the diluent to add and the dilution factor. A serial dilution table shows the concentration in each tube when a fixed volume is carried along a series.

How C1V1 = C2V2 works

When you dilute a solution, the amount of dissolved substance stays the same while the volume grows, so concentration × volume is constant: C₁V₁ = C₂V₂. Here C₁ and V₁ are the stock's concentration and the volume you take, and C₂ and V₂ are the final concentration and total volume. To make 500 mL of a 50 mM solution from a 1 M stock, you need 1 M × V₁ = 0.05 M × 500 mL, so V₁ = 25 mL of stock, made up to 500 mL with 475 mL of diluent. That is a 1 in 20 dilution. The rule works with any units as long as both concentrations use the same unit and both volumes use the same unit, and the calculator converts mixed units for you. Serial dilutions repeat a fixed step. Moving 100 µL into 900 µL of diluent each time gives a tenfold drop per tube, so three tubes take a 1 M stock to 1 mM, the standard way to reach very low concentrations accurately. Good practice is to add the stock to most of the diluent, then make up to the final volume. With strong acids, always add the acid to the water, never the reverse. The molar mass calculator converts grams to moles, the pH calculator checks the result and the unit converter handles other units. Ratios explained: how to simplify, scale, and divide an amount in a given ratio explains dilution ratios.

Frequently asked questions