How this dilution calculator works
When you dilute a solution you add solvent without changing the amount of dissolved solute. That conservation of solute is exactly what the dilution equation C1V1 = C2V2 captures: concentration multiplied by volume gives the quantity of solute, and that product is the same before and after dilution.
The calculator detects which of the four fields you left blank and rearranges the formula to solve for it. To find the stock volume use V1 = C2·V2 / C1; for the final volume use V2 = C1·V1 / C2; for a concentration use C2 = C1·V1 / V2 or C1 = C2·V2 / V1. When both volumes are known it also reports the solvent to add, which is simply V2 − V1.
Reference note: this is a neutral lab-math tool. Keep C1 and C2 in the same concentration unit and V1 and V2 in the same volume unit. The percentage and mg/mL options follow the same proportional relationship. Always follow your own institution's safety procedures.
Frequently asked questions
- What is the dilution formula?
- The dilution formula is C1V1 = C2V2, where C1 and V1 are the concentration and volume of the concentrated stock and C2 and V2 are those of the final, diluted solution. Because the amount of solute does not change, the product of concentration and volume stays constant.
- How do I dilute a stock solution?
- Choose your final concentration (C2) and final volume (V2), then solve for the stock volume: V1 = C2 × V2 / C1. Measure that volume of stock and add solvent up to V2. Leave the stock-volume field blank and the calculator does it for you.
- How much solvent do I add?
- The solvent (diluent) to add equals the final volume minus the stock volume, V2 − V1. For example, reaching 100 mL from 25 mL of stock means adding 75 mL of solvent. The tool shows this whenever both volumes are known.
- What units should I use?
- C1 and C2 must share one concentration unit (both M, or both mg/mL, etc.) and V1 and V2 must share one volume unit. The calculator treats the two concentrations as the same unit and the two volumes as the same unit so the formula stays consistent.
- What is a dilution factor?
- The dilution factor is how many times more dilute the final solution is than the stock. It equals C1 / C2, which also equals V2 / V1. A factor of 4 (written 1:4) means one part stock diluted to four parts total volume.
- Can I increase concentration by dilution?
- No. Adding solvent can only keep concentration the same or lower it, so C2 must be less than or equal to C1. To raise concentration you would evaporate solvent or add more solute, which the dilution formula does not cover.