Dilution Calculator
The dilution calculator uses the equation C1V1 = C2V2 to solve for any unknown variable when diluting solutions in the laboratory. Dilution calculations are performed daily in analytical chemistry, biochemistry, clinical laboratories, pharmaceutical manufacturing, and microbiology. Whether preparing standard solutions from concentrated stock, making working solutions from reagent bottles, or setting up calibration standards across a concentration range, the fundamental dilution equation applies. Enter any three of the four values to instantly find the missing variable, and use the results to prepare accurate solutions in the lab.
Dilution formula
C1 * V1 = C2 * V2
V1 = (C2 * V2) / C1 (volume of stock to take)
C2 = (C1 * V1) / V2 (final concentration)
Dilution factor = C2 / C1 = V1 / V2
Solvent to add = V2 - V1
Serial dilution
- For n serial dilutions each with factor DF, total factor = DF^n.
- A 1:10 dilution repeated 3 times gives 1:1000 (0.001 of original).
- Total DF = individual DF1 x DF2 x DF3 x ...
- Concentration after serial dilution: C_final = C_initial * (total DF).
Dilution: frequently asked questions
What is the dilution equation?
The dilution equation C1V1 = C2V2 states that the moles of solute before dilution equals the moles after dilution. C1 is initial concentration, V1 is initial volume taken, C2 is the final (target) concentration, and V2 is the final total volume. Adding solvent increases volume but does not change the number of moles of solute.
How do I calculate how much stock solution to use?
Rearrange to V1 = (C2 * V2) / C1. For example, to prepare 500 mL of 0.1 M NaCl from a 1.0 M stock: V1 = (0.1 * 500) / 1.0 = 50 mL. Take 50 mL of stock solution and dilute to 500 mL total volume by adding 450 mL of solvent.
What is a serial dilution?
A serial dilution is a stepwise sequence of dilutions, each using the diluted solution from the previous step. If each step has a 1:10 ratio, after 3 steps the dilution factor is 1:1000. Serial dilutions are used in microbiology (colony counting), immunology (antibody titration), and pharmacology to prepare a range of concentrations spanning many orders of magnitude.
What is the dilution factor?
The dilution factor (DF) = C2/C1 = V1/V2. It represents how much the concentration has decreased. A 1:10 dilution has DF = 0.1 (or is described as a 10-fold dilution). The concentration after dilution is: C2 = C1 / dilution_factor. Multiple dilutions: multiply the individual dilution factors to get the total dilution factor.
What concentration units can I use?
Any consistent units can be used for concentration (mol/L, mg/mL, %, w/v, ppm, etc.) as long as C1 and C2 use the same units. Volume units for V1 and V2 must also match (both in mL, L, or uL). The calculation works identically regardless of units because C1V1 = C2V2 is a statement about the conservation of moles (or mass) of solute.
Official sources
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology.