Work out stock solution instantly with clear inputs, formula shown and shareable results.
A stock solution is a concentrate, so the working solution is made by pipetting a small measured volume of stock and topping up with diluent. The stock volume is the working concentration times the working volume divided by the stock concentration - a 10 M stock taken to 0.4 M in 250 mL needs 10 mL of stock and 240 mL of diluent, a 25-fold dilution.
Volume of stock
V(stock) = C(working) x V(working) / C(stock)
Fold dilution
fold = C(stock) / C(working)
It cannot be reached by dilution, so the calculator flags it rather than returning a negative diluent volume.
Serial dilution protocols are usually written as folds (1:25 here), so it is the figure you carry to the bench.