How It Works
This calculator works in 4 steps.
Enter the stock concentration (C₁)
Type the concentration printed on the stock bottle or certificate of analysis.
Enter the stock volume transferred (V₁)
Type the exact volume pipetted, including any rounding applied at the bench.
Enter the final volume (V₂)
Type the total volume after diluent addition, not the diluent volume alone.
Read the final concentration
The calculator multiplies C₁ by V₁, divides by V₂, and reports C₂ with the fold dilution V₂ / V₁.
The Formula
The formula multiplies the stock concentration by the ratio of stock volume to final volume.
C₂ = C₁ × (V₁ / V₂)Fold = V₂ / V₁ = C₁ / C₂- C₂:
- Concentration after dilution
- C₁:
- Stock concentration
- V₁:
- Volume of stock added
- V₂:
- Total volume after dilution
Pipetting 5 mL of 10 mM stock into a flask filled to 50 mL gives C₂ = 10 × 5 / 50 = 1 mM, a 10-fold dilution.
Conversion Table
The conversion table gives the final concentration and fold dilution for 6 stock-volume and final-volume pairs.
| Stock (C₁) | Stock added (V₁) | Final volume (V₂) | Final concentration (C₂) | Fold |
|---|---|---|---|---|
| 1 M | 1 mL | 10 mL | 0.1 M | 10× |
| 10 mM | 5 mL | 50 mL | 1 mM | 10× |
| 100 µg/mL | 0.2 mL | 20 mL | 1 µg/mL | 100× |
| 70 % v/v | 70 mL | 100 mL | 49 % v/v | 1.429× |
| 5 mg/mL | 2 mL | 1,000 mL | 0.01 mg/mL | 500× |
| 1,000 µM | 0.01 mL | 1 mL | 10 µM | 100× |
What Is the Final Concentration Calculator?
The Final Concentration Calculator is a dilution tool that returns the concentration (C₂) of a solution after a known stock volume is brought to a known final volume. The tool answers the question "what strength did I make?" after a transfer, rather than "how much stock do I need?" before it.
Final concentration is the value written on the tube label and entered into downstream calculations. The calculator accepts molar, mass, and percent units, and returns C₂ in the same unit as C₁. The result assumes a solute-free diluent and a final volume measured after mixing.
Common Uses
There are 5 main uses of this calculator.
Tube label verification
Users confirm the concentration to print on a tube after the dilution is complete.
Pipette rounding checks
Technicians recalculate C₂ when a 2.37 µL transfer is rounded to 2.4 µL.
Assay reporting
Researchers report the exact working concentration in methods sections and lab notebooks.
Preparation error recovery
Staff calculate the real concentration when too much diluent went into a flask.
Quality records
QC teams document the expected concentration for comparison with a measured value.