How It Works
This calculator works in 4 steps.
Choose concentration or volume mode
Select concentration mode for C₁ and C₂, or volume mode for V₁ and V₂.
Enter the 2 values
Type the stock and final concentrations in one unit, or the stock and final volumes in one unit.
Divide the larger value by the smaller
The calculator returns DF = C₁ / C₂ or DF = V₂ / V₁.
Read the DF forms
The result shows DF as a number, as the fraction 1/DF, and as the percent of the original strength.
The Formula
The formula divides stock concentration by final concentration, or final volume by stock volume.
DF = C₁ / C₂DF = V₂ / V₁% of stock = 100 / DF- DF:
- Dilution factor (unitless)
- C₁ / C₂:
- Stock and final concentrations
- V₁ / V₂:
- Stock and final volumes
A 100 mM stock diluted to 5 mM has DF = 100 / 5 = 20. The final solution holds 1/20 (5%) of the stock concentration.
Conversion Table
The conversion table converts 7 stock and final concentration pairs into DF, dilution fraction, and remaining percent.
| Stock (C₁) | Final (C₂) | Dilution factor | Fraction (1/DF) | Remaining strength |
|---|---|---|---|---|
| 10 mM | 1 mM | 10 | 0.1 | 10% |
| 100 mM | 5 mM | 20 | 0.05 | 5% |
| 1 mM | 0.25 mM | 4 | 0.25 | 25% |
| 50 mM | 2 mM | 25 | 0.04 | 4% |
| 1,000 mM | 1 mM | 1,000 | 0.001 | 0.1% |
| 12 mM | 3 mM | 4 | 0.25 | 25% |
| 6 mM | 0.06 mM | 100 | 0.01 | 1% |
What Is the Dilution Factor Calculator?
The Dilution Factor Calculator is a tool that returns the dilution factor (DF), the number of times a stock concentration is reduced to reach a final concentration. A DF of 10 means the final solution holds one-tenth of the stock concentration.
The dilution factor is unitless. The calculator computes DF from concentrations (C₁ / C₂) or from volumes (V₂ / V₁), and both paths give the same number for a single dilution. DF is always 1 or greater; a value below 1 signals a concentration step, not a dilution.
Common Uses
There are 5 main uses of this calculator.
Measured result correction
Analysts multiply an instrument reading by DF to report the original sample concentration.
Protocol interpretation
Users convert a protocol instruction, such as "dilute 50-fold", into volumes.
Serial dilution planning
Microbiologists combine per-step DF values into an overall DF.
Method validation
Validation teams test dilution linearity at DF values of 2, 5, 10, and 100.
Lab report calculations
Students show DF in titration, spectrophotometry, and plating reports.