Dilution Calculator
Find how much stock solution you need to make a weaker solution — or any of the other three quantities. The amount of dissolved substance stays the same when you add solvent.
What is a Dilution?
Diluting means adding solvent (usually water) to a solution. The amount of dissolved substance does not change — it is just spread over a larger volume. Since amount = concentration × volume, the product C·V is the same before and after.
In the lab you rarely weigh out tiny amounts directly. Instead you make a concentrated stock solution once, and dilute portions of it whenever you need a weaker one.
Live Diagram
1 : 4Common Dilution Ratios
for 100 mL final| Ratio | Factor | Stock | Solvent |
|---|---|---|---|
| 1 : 2 | 2× | 50 mL | 50 mL |
| 1 : 4 | 4× | 25 mL | 75 mL |
| 1 : 5 | 5× | 20 mL | 80 mL |
| 1 : 10 | 10× | 10 mL | 90 mL |
| 1 : 100 | 100× | 1 mL | 99 mL |
| 1 : 1000 | 1000× | 0.1 mL | 99.9 mL |
In the Lab
Both sides are the number of moles of solute. Adding solvent changes the volume and the concentration, but not the moles.
Pipette the stock into a volumetric flask, then add solvent up to the mark. Filling to V₂ is more accurate than adding V₂ − V₁, because volumes are not always additive.
A 1 : 10 dilution means one part stock in ten parts total. For very large factors, use several smaller steps (a serial dilution).
Sources & Verification
- S. S. Zumdahl & S. A. Zumdahl, Chemistry, 10th ed., Cengage, 2018 — Ch. 4 (Types of Chemical Reactions and Solution Stoichiometry).