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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)



    • Concentration solution converter

    gram/liter, kilogram/liter [kg/L], milligram/liter [mg/L], part/million [ppm], grain/gallon (US) [gr/gal (US)], grain/gallon (UK) [gr/gal (UK)], pound/gallon (US) [lb/gal (US)], pound/gal (UK) [lb/gal (UK)] ...