Protein Concentration Calculator

Protein Concentration Calculator (OD260/OD280)

OD280 Value
OD260 Value
Protein (very pure) Concentration (mg/ml)
Protein (Contaminated) Concentration (mg/ml)


  • Unknown pure proteins or protein mixtures: Use the following formula to roughly estimate protein concentration. Protein Concentration (mg/ml) = OD280 divided by cuvette width (cm)
  • Pure protein of known absorbance coefficient. Protein concentration = OD280 divided by (absorbance coefficient * cuvette width)
  • Unknown protein with possible nucleic acid contamination. Use the following formula to estimate protein concentration: Protein Concentration (mg/ml) = (1.55 * OD280) – (0.76 * OD260)
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