How to use
- Enter the stock concentration, the target concentration and the target volume.
- The result card shows the volume of stock to transfer, with the volume of solvent to add underneath it.
- A single line below that states the preparation as an instruction you can follow directly.
- Concentration and volume each have their own unit.
Exponents can be entered with e — for example, 1.5×10⁻⁵ is entered as 1.5e-5.
Formula & notes
This calculator uses the same equation as the dilution calculator, C1V1 = C2V2, but presents the answer from the bench's point of view. Where the dilution calculator fills in a blank, this one tells you what to mix and how much of it.
- Stock to transfer
- V1 = C2 × V2 ÷ C1
- Solvent to add
- V_solvent = V2 − V1
V2 here is the final volume you are making. Add V2 − V1 of solvent to V1 of stock and the whole comes to V2 at concentration C2.
Practical notes
- The solvent figure is what you add, not what you end up with. Swapping the two puts the concentration out, which is why the result card keeps them apart.
- For solutions whose volumes do not add — concentrated solutions, alcohols — it is more accurate to make up to the final volume in a volumetric flask than to add the calculated amount of solvent.
- When the stock volume works out very small, below about 1 μL, pipetting error dominates. Add an intermediate dilution, or make a larger batch.
- Viscous solutions cling to the pipette wall. Use reverse pipetting, or rinse the tip into the vessel.
- If the stock is less concentrated than the target, dilution cannot get you there and the calculation does not hold.