Dilution & Molarity Calculator (C₁V₁ = C₂V₂)
C₁V₁ = C₂V₂ dilution calculator: stock in mM, target in µM, final volume in mL, giving the stock and diluent volumes to pipette.
How it works
Dilutions are solved with the conservation relation C₁V₁ = C₂V₂, where C₁ is stock concentration, C₂ the target concentration, and V₂ the desired final volume. The tool takes the stock in millimolar, the target in micromolar and the final volume in millilitres, and returns the stock volume in microlitres and the diluent volume to add. It refuses a target more concentrated than the stock rather than printing a negative volume.
Frequently asked questions
How do I calculate a dilution?
Use C₁V₁ = C₂V₂. Multiply your target concentration by your final volume, then divide by your stock concentration, to get the volume of stock needed. Subtract that from the final volume to get the diluent to add. For example, to make 20 mL at 25 µM from a 100 mM stock: (25 µM × 20 mL) ÷ 100 mM = 5 µL of stock, made up with 19.995 mL of buffer.
What is a serial dilution and when should I use one?
A serial dilution is a stepwise sequence in which each step dilutes the product of the previous one by a fixed factor, commonly ten-fold or two-fold. It is the practical way to reach very low concentrations, because pipetting sub-microlitre volumes directly from a concentrated stock is inaccurate. The trade-off is that pipetting error compounds along the series, so the last point carries the most uncertainty.