Dilution Calculator
Find how much stock you need for a dilution, or the final concentration or volume, with C₁V₁ = C₂V₂. Works in molar, mass, percent and X units.
Calculator
Dilute a stock
Enter the stock concentration, final concentration and final volume to see the stock volume.
Worked example
100 µL of 10 µM primer from a 100 µM stock
- 01C₁ = 100 µM, C₂ = 10 µM, V₂ = 100 µL
- 02V₁ = C₂ × V₂ ÷ C₁ = 10 × 100 ÷ 100
- 03V₁ = 10 µL
Mix 10 µL of stock with 90 µL of water.
How it works
The reasoning behind it
When you dilute a solution, the amount of what is dissolved stays the same; only the volume around it grows. The amount is concentration times volume, so what you take from the stock (C₁ × V₁) equals what ends up in the new solution (C₂ × V₂).
Any three of the four values give the fourth. The usual question is how much stock to take: V₁ = C₂ × V₂ ÷ C₁.
C₁ ÷ C₂ is the dilution factor. 10 µL of stock in 100 µL in total is a 10-fold dilution, also written 1 in 10 or 1/10.
Questions
Frequently asked
What does C1V1 = C2V2 mean?
It says the amount of what is dissolved is the same before and after a dilution. C1 and V1 are the concentration and volume of the stock you take; C2 and V2 are the concentration and total volume of what you make.
How do I dilute a 10X buffer to 1X?
Use 1 part 10X buffer for every 10 parts of final volume. For 500 mL of 1X, take 50 mL of 10X and add 450 mL of water.
Can I use different units for C1 and C2?
Yes, as long as they measure the same thing: mM and µM convert into each other, and so do mg/mL and µg/mL. Molar and mass units can't be mixed without the formula weight.
What is the difference between a dilution factor and a dilution ratio?
A dilution factor of 10 means the result is 10 times weaker: 1 part stock in 10 parts in total. A ratio of 1:10 sometimes means the same and sometimes 1 part stock plus 10 parts diluent, which is 1 in 11. Saying 1 in 10, or giving the factor, avoids the confusion.
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