Dilution factor calculator: the core idea
When you dilute a solution, the amount of solute stays the same—only the total volume changes.
That is why concentration decreases in proportion to the volume increase.
\[
\begin{aligned}
C_1 \cdot V_1 &= C_2 \cdot V_2 \\
DF &= \frac{C_1}{C_2} = \frac{V_2}{V_1}
\end{aligned}
\]
Here:
C1 = stock concentration,
V1 = volume taken from stock,
C2 = final concentration,
V2 = final volume after adding diluent.
Solving for any unknown
The same equation can be rearranged depending on which value you want to compute.
The calculator highlights the chosen unknown and locks the other three.
\[
\begin{aligned}
C_1 &= \frac{C_2 \cdot V_2}{V_1} \\
V_1 &= \frac{C_2 \cdot V_2}{C_1} \\
C_2 &= \frac{C_1 \cdot V_1}{V_2} \\
V_2 &= \frac{C_1 \cdot V_1}{C_2}
\end{aligned}
\]
Common lab question: “How much stock do I pipette?”
Choose unknown V1, then enter C1,
C2, and V2.
The diluent volume is:
\[
\begin{aligned}
V_{\text{diluent}} &= V_2 - V_1
\end{aligned}
\]
Dilution factor and ratio form
The dilution factor tells you how many times you reduce the concentration:
if DF = 50, then the final solution is 50 times less concentrated than the stock.
\[
\begin{aligned}
DF &= \frac{C_1}{C_2} \\
\text{Ratio form} &\approx 1:DF
\end{aligned}
\]
Example interpretation: “1:50” means 1 part stock + 49 parts diluent (to reach 50 total parts).
In practice, you set an actual final volume V2 and compute the needed
stock volume V1.
Units and compatibility checks
This calculator supports molar concentration units and a mass-based concentration unit:
M, mM, µM, and mg/mL.
Important rule
You must keep C1 and C2 in the same “family”.
Molar units (M, mM, µM) are compatible with each other, but mg/mL is not directly compatible
unless you also know the molar mass (that conversion is a different calculator).
Volumes are normalized internally to mL so the substitution is consistent. You can input or output using
µL, mL, or L.
How to sanity-check your dilution
- If you are diluting: you expect C2 < C1 and V2 > V1.
- DF should be greater than 1 for a true dilution.
- The diluent volume must be non-negative: V2 − V1 ≥ 0.
The calculator shows warnings when your inputs imply concentrating rather than diluting, or when the computed
diluent becomes negative.
