Solution dilution calculator

Preparing a target concentration

If dilution preserves the amount of dissolved substance, concentration multiplied by volume is the same before and after dilution. Divide target concentration times final volume by stock concentration to obtain the stock aliquot. For example, preparing 250 mL at 0.1 mol/L from a 1 mol/L stock requires 25 mL of stock.

What final volume means

The 250 mL is the volume of the completed solution. Liquid volumes are not always additive, so the tool does not state an exact volume of solvent to add. Reaction, volatility, precipitation and temperature changes are outside the model. The numerical result is not a laboratory procedure.

Verify the amount of solute

Use stock concentration 0.8 mol/L, target concentration 0.2 mol/L and final volume 400 mL. Required stock volume is 0.2 × 400 / 0.8 = 100 mL. Initial solute amount is 0.8 × 0.100 = 0.080 mol and the final amount is 0.2 × 0.400 = 0.080 mol. Their equality checks conservation of solute. The volume ratio is four, consistent with a target concentration four times lower than the stock.

This result is not an instruction to measure and add exactly 300 mL of solvent. Final volume is the measured volume of the complete solution, including the stock. Match units before comparing concentration and volume products.

Use the final concentration mode to check a known stock volume and final volume. In serial dilution, the final solution from each stage becomes the next stage's stock. Do not reuse the original stock concentration at every stage. If the solvent already contains the solute, or reaction occurs on mixing, this single stock balance is insufficient. Actual preparation requires an appropriate laboratory procedure.

Frequently asked questions

How much stock solution is needed?

For example, to prepare 250 mL of solution at 0.1 mol/L from stock at 1 mol/L, use 25 mL of stock. This preliminary calculation conserves concentration times volume without assuming separate liquid volumes add up, and it excludes heat release, chemical compatibility and safe mixing order, so the procedure must follow the safety data sheet.

Calculate with these values