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Calcimator

Protein Concentration Calculator

Protein quantification from Bradford/BCA assay data using Beer-Lambert Law (A = εlc).

Inputs

Results

Concentration (mg/mL)

0

Concentration (µg/mL)0.76
Concentration (µM)11.41
Concentration (M)0
Total protein (mg)0
A280-based conc. (mg/mL)0
How to Use This Calculator
  1. Enter the absorbance reading from your spectrophotometer and the molar extinction coefficient (ε).
  2. Set path length (cm), molecular weight (Da), dilution factor, and sample volume (mL).
  3. Review Concentration in mg/mL, µg/mL, and µM.
  4. Use Total Protein (mg) to calculate yield across the full sample volume.

What each input means

Absorbance (A)
Measured absorbance from spectrophotometer (unitless, typically 0-3).
Extinction coefficient (ε)
Molar extinction coefficient in L/(mol·cm). BSA at 280nm ≈ 43,824.
Path length (cm)
Cuvette path length in cm. Standard cuvette = 1 cm.
Molecular weight (Da)
Protein molecular weight in Daltons. BSA = 66,430 Da.
Dilution factor
Sample dilution factor (e.g., 10 for 1:10 dilution).
Sample volume (mL)
Total sample volume in mL for total protein calculation.

What each result means

Concentration (mg/mL)
Protein concentration in milligrams per milliliter.
Concentration (µg/mL)
Protein concentration in micrograms per milliliter.
Concentration (µM)
Protein concentration in micromolar.
Concentration (M)
Protein molar concentration in mol/L.
Total protein (mg)
Total protein mass in the sample volume.
A280-based conc. (mg/mL)
Concentration calculated from A280 absorbance.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Absorbance (A) = 0.5, Extinction coefficient (ε) = 43824, Path length (cm) = 1, Molecular weight (Da) = 66430 = 6 input(s) provided
  2. Calculate Concentration
    Concentration = mgPerMl * dilutionFactor
    0.001 = 0.001
  3. Calculate Concentration
    Concentration = mgPerMl * dilutionFactor
    0.76 = 0.76
  4. Calculate Concentration
    Concentration = molarConcentration * dilutionFactor * 1e6
    11.41 = 11.41

Engine last updated . Checked against 2 independently-derived tests — how we verify calculators.

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