Work out how much stock solution and how much diluent you need to reach a target concentration and volume.
The method behind this calculator
The dilution equation states that the amount of solute stays constant: concentration times volume before equals concentration times volume after. Rearranged, it tells you the stock volume to draw for any target.
The calculator also reports the diluent volume separately, which is the number you actually measure out at the bench, and the dilution factor for labelling.
How to use it
- Enter the stock concentration and your target concentration.
- Enter the final volume you want to end up with.
- Read the stock volume to take and the diluent to add.
The formula
CāVā = CāVā ā Vā = CāVā Ć· Cā
diluent to add = Vā ā Vā Ā· dilution factor = Cā Ć· Cā
A worked example
On the values this calculator opens with, the stock volume (Vā) is 10 mL. Underneath, Stock volume needed comes out at 10 mL and Diluent to add at 90 mL. Change any field and every figure updates as you type.
Questions people ask about this
Do the concentration units matter?
Only that both concentrations use the same unit. Molarity, percentage or mg/mL all work as long as they match.
What is a 1:10 dilution?
One part stock to nine parts diluent, giving a total of ten parts ā a dilution factor of 10.
Why calculate diluent separately?
Because you add solvent to the stock, not to an empty final volume. Measuring the diluent directly avoids overshooting.