How do you use C1V1 = C2V2?
C1 and V1 are the concentration and volume of the stock; C2 and V2 are the concentration and volume you want. Diluting does not change the amount of solute, so C1 x V1 = C2 x V2. Fill in three values and solve for the fourth. Both concentrations must be in the same kind of unit, for example both molar, and the calculator converts within that kind.
Worked example: to make 100 mL of 0.1 M from a 1 M stock, V1 = 0.1 M x 100 mL ÷ 1 M = 10 mL. Add 10 mL of stock to 90 mL of diluent.
How do you calculate a dilution factor?
Dilution factor = C1 ÷ C2, or equivalently V2 ÷ V1. Going from 10 mM to 100 µM is a 100-fold dilution, often written 1:100, meaning one part stock in 100 parts total. For dilutions over about 1,000-fold, the stock volume can fall below what a pipette measures accurately; the calculator warns you below 1 µL so you can make an intermediate dilution first.
How do I dilute in steps or make a series?
For a set of concentrations, each a fixed fold apart, use the Serial Dilution Calculator. For making the stock from a solid, start with the Molarity Calculator.
Frequently asked questions
What is C1V1 = C2V2 used for?
Working out how much of a concentrated stock to dilute to reach a target concentration and volume. It holds because diluting adds solvent but not solute.
What units do I use in C1V1 = C2V2?
Any, as long as both concentrations use the same kind of unit and both volumes are volumes. The calculator converts M, mM, µM, nM and pM, or mg/mL, µg/mL and ng/mL, and L, mL, µL and nL.
How do you make a 1:10 dilution?
Mix one part stock with nine parts diluent, for example 100 µL of stock with 900 µL of diluent for 1 mL in total.
Why does the calculator say the dilution is not possible?
Because the target concentration is higher than the stock. Dilution can only lower concentration.
What is the C1V1 = C2V2 equation called?
It is usually just called the dilution equation. It follows from conservation of the amount of solute.
Is anything I enter saved or sent?
No. The calculator runs in your browser. Nothing you type is saved, sent to BioBridgeX or added to the page address, and analytics never see your numbers.
Related free tools
- Serial Dilution Calculator: Transfer and diluent volumes and a concentration table for 2-fold, 3-fold, half-log or 10-fold series.
- Molarity Calculator: Mass to weigh, volume to add or molar concentration from the molecular weight, with units and steps.
- Antibody Dilution Calculator: Antibody and buffer volumes from a 1:X ratio or a stock and working concentration.
- All lab calculators and every free tool on BioBridgeX.
Sources
Check every result before use. Formulas assume ideal conditions; follow your validated lab procedures and the reagent supplier's instructions. Facts on this page last checked 27 October 2026.
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