This dilution calculator solves the dilution equation C1V1 = C2V2. Enter the three values you know — stock concentration, desired concentration and final volume — and it finds the fourth: exactly how much stock solution and solvent to mix.
What Is a Dilution Calculator?
A dilution calculator works out how to weaken a concentrated stock solution to a target concentration. Diluting does not change the amount of solute — only the volume it is spread through — which gives the conservation equation below. This tool is the natural companion to our Molarity Calculator and part of the Chemistry Calculators collection.
The Dilution Equation
C1V1 = C2V2 — stock concentration × stock volume = final concentration × final volume.
Worked example (verified): make 500 mL of 0.1 M solution from a 2 M stock. V1 = (0.1 × 500) ÷ 2 = 25 mL of stock, plus 475 mL of solvent — a 20× dilution. The units of C and V cancel as long as you use the same units on both sides (mol/L with mL is fine, because both volumes share the unit).
How to Dilute Safely and Accurately
- Calculate first, then measure the stock with a pipette or graduated cylinder — never guess.
- Put most of the solvent in the flask first, add the stock, then top up to the mark (final volume is V2, not “V2 of added solvent” — close enough for most purposes, but volumetric glassware exists for a reason).
- Strong acids and bases: always add the concentrate to water, never the reverse, and expect heat.
- For very large dilution factors (1000×+), use serial dilution: two 10× steps and one 100× step beat trying to pipette a fraction of a microliter.
- Label the new bottle with concentration, date and contents immediately.
Dilution Factor
The dilution factor is C1 ÷ C2 (equivalently V2 ÷ V1): how many times weaker the final solution is. A “1:10 dilution” in lab slang usually means 1 part stock in 10 parts total — dilution factor 10. Microbiologists use it for plate counts, pharmacists for dose preparation, and photographers for developer mixing; the mathematics is identical. Prepare the stock itself with our Molar Mass Calculator for the weighing step.
Related Tools
- Molarity Calculator — concentration from moles, mass and volume
- Molar Mass Calculator — molecular weights for weighing solutes
- Chemistry Calculators — the full chemistry collection
Frequently Asked Questions
What does C1V1 = C2V2 mean?
The amount of solute before dilution (concentration × volume of stock) equals the amount after dilution (final concentration × final volume), because dilution only adds solvent.
How do I dilute 2 M to 0.1 M?
The dilution factor is 20. For 500 mL final: 500 ÷ 20 = 25 mL stock, topped up to 500 mL with solvent — as in the worked example.
What is a serial dilution?
A chain of dilutions where each step dilutes the previous solution further (e.g., three 10× steps = 1000× total). It achieves huge factors with practical volumes.
Does the solvent volume equal V2 − V1?
Approximately, for dilute aqueous solutions. Strictly, you should dilute to the final volume V2 in volumetric glassware, since liquid volumes are not always perfectly additive.
Can I use this for percent or ppm concentrations?
Yes — the equation works for any consistent concentration unit (%, ppm, mg/L), as long as C1 and C2 use the same unit.
Is this dilution calculator free?
Yes — free, instant, no sign-up.