Home › Calculators › Dilution Calculator

Dilution Calculator

Find how much stock solution and diluent you need, or what concentration you end up with, using C₁V₁ = C₂V₂. Concentrations can be molar, mass per volume, percent, ppm or fold (10× to 1×), and volume units can differ.

Solve for

Stock volume V₁Stock concentration C₁Final concentration C₂Final volume V₂

Stock solution

Stock concentration (C₁)

Unit (C₁)

Stock volume (V₁)

Unit (V₁)

Final (diluted) solution

Final concentration (C₂)

Unit (C₂)

Final volume (V₂)

Unit (V₂)

Enter your values to see the result.

How to use the Dilution Calculator

Choose what to solve for, usually the stock volume V₁.
Enter the stock concentration and the final concentration you want, using the same kind of unit (for example M and mM).
Enter the final volume you need and pick the volume units.
Measure the stock volume shown, then add diluent until you reach the final volume.
Use the table to scale the same dilution up or down.

The dilution equation

When you dilute a solution, the amount of solute does not change, only the volume it is spread through. That gives:

C₁ × V₁ = C₂ × V₂
Stock volume: V₁ = C₂ × V₂ ÷ C₁
Final volume: V₂ = C₁ × V₁ ÷ C₂
Final concentration: C₂ = C₁ × V₁ ÷ V₂
Diluent to add: V₂ − V₁; dilution factor: C₁ ÷ C₂

Example: to make 250 mL of 50 mM solution from a 1 M (1,000 mM) stock, V₁ = 50 × 250 ÷ 1,000 = 12.5 mL of stock, topped up with 237.5 mL of diluent.

Common dilutions at a glance

Dilution	Dilution factor	Stock for 100 mL	Diluent for 100 mL	For 1 L
1:2 (half strength)	2	50 mL	50 mL	500 mL + 500 mL
1:5	5	20 mL	80 mL	200 mL + 800 mL
1:10 (10× to 1×)	10	10 mL	90 mL	100 mL + 900 mL
1:20 (20× to 1×)	20	5 mL	95 mL	50 mL + 950 mL
1:50	50	2 mL	98 mL	20 mL + 980 mL
1:100	100	1 mL	99 mL	10 mL + 990 mL
1:1000	1,000	0.1 mL (100 µL)	99.9 mL	1 mL + 999 mL

Here "1:10" means 1 part stock in 10 parts total. For serial dilutions, repeat the same step: three 1:10 steps give a 1:1000 overall dilution.

Frequently asked questions

What does C1V1 = C2V2 mean?

It says the amount of solute stays the same when you dilute: concentration times volume before (stock, C₁ × V₁) equals concentration times volume after (final, C₂ × V₂). Rearranging gives V₁ = C₂V₂ ÷ C₁, the stock volume you need.

How much diluent do I add?

Add V₂ − V₁. For example, to make 500 mL of 100 mM from a 1 M stock you need 50 mL of stock plus 450 mL of water or buffer, for a total of 500 mL.

What is a dilution factor?

The dilution factor is C₁ ÷ C₂, which also equals V₂ ÷ V₁. A 1:10 dilution (1 part stock in 10 parts total) has a dilution factor of 10. Note that some people write 1:10 to mean 1 part stock plus 10 parts diluent, so check which convention is being used.

Can I mix molar and mass units?

Not directly. Converting between molarity and g/L requires the molar mass of the solute (g/L = M × g/mol). Use the same family of units for C₁ and C₂, or convert first with a molarity calculator.

Does C1V1 = C2V2 work for percentages?

Yes, as long as both concentrations use the same kind of percent (w/v, v/v or w/w) and you dilute by volume. For mixing two solutions that both contain the solute, use a mixing (alligation) calculation instead.

Why is the volume sometimes not exactly additive?

Some liquids, such as ethanol and water, shrink slightly when mixed. For accurate work, add stock to a volumetric flask and fill to the mark with diluent instead of adding two measured volumes.

Related tools