How to Use Protein Concentration Calculator
The Protein Concentration Calculator is a versatile online tool that covers the three most common methods used in biochemistry labs to quantify protein samples. Select the method that matches your experimental setup, fill in the required values, and the Protein Concentration Calculator returns the result instantly.
- Choose a calculation method — Select Beer-Lambert Law, Dilution Formula, or Standard Curve at the top of the tool.
- Select your concentration unit — Choose from mg/mL, µg/mL, g/L, or mol/L to match your reporting needs.
- Enter the required inputs — Each mode of the Protein Concentration Calculator shows only the fields relevant to that method.
- The Protein Concentration Calculator displays the computed concentration together with the formula used.
Formula & Theory — Protein Concentration Calculator
The Protein Concentration Calculator supports three scientifically validated methods:
Beer-Lambert Law
C = A / (ε × l)
| Symbol | Meaning |
|---|---|
| A | Absorbance (unitless) |
| ε | Molar extinction coefficient (L·mol⁻¹·cm⁻¹ or mL·mg⁻¹·cm⁻¹) |
| l | Path length (cm, typically 1 cm) |
| C | Protein concentration |
This is best suited for pure, well-characterized proteins with known ε values, such as BSA or specific enzymes at 280 nm.
Dilution Formula
C2 = C1 × V1 / V2
Use this mode of the Protein Concentration Calculator when you have diluted a stock protein solution and need to find the final working concentration.
Standard Curve Method
C = (A − b) / m
| Symbol | Meaning |
|---|---|
| A | Sample absorbance |
| m | Slope of the standard curve |
| b | Y-intercept of the standard curve |
This method is the basis of Bradford, BCA, and Lowry assays. Run a calibration series with known concentrations, fit a linear regression, then enter the slope and intercept into the Protein Concentration Calculator.
Use Cases for Protein Concentration Calculator
The Protein Concentration Calculator is indispensable across a wide range of laboratory workflows:
- Spectrophotometric quantification — Use Beer-Lambert mode to calculate concentration directly from A280 readings for pure protein samples.
- Bradford / BCA / Lowry assays — Use standard curve mode to convert raw absorbance into concentration for complex protein mixtures.
- Preparation of working solutions — Use dilution mode to calculate the volume of stock protein needed when preparing diluted standards or reagents.
- Western blot loading normalization — Ensure equal protein loading per lane by using the Protein Concentration Calculator to adjust all samples to the same concentration.
- Enzyme kinetics — Precisely determine substrate or enzyme concentrations before kinetic assays.
Whether you work with recombinant proteins, cell lysates, or serum samples, the Protein Concentration Calculator helps you obtain accurate, reproducible quantification results.