How this calculator works
Beer-Lambert proportionality relates absorbance to concentration and optical path. NanoDrop lists A1% values of 6.7 for BSA, 13.7 for IgG and 26.4 for lysozyme; dividing by ten gives coefficients for concentration in mg/mL. For other proteins, pigments or nucleotides, enter a verified coefficient at the measured wavelength rather than borrowing an unrelated protein value. This tool does not model Bradford or BCA calibration curves.
Formula
C (mg/mL) = A × dilution / (mass coefficient × path in cm). Mass coefficient = molar epsilon / molecular weight. mg/mL is numerically equal to g/L. A1% is the absorbance of 10 mg/mL at 1 cm.
Worked example
BSA at absorbance 0.67, 1 cm path and no dilution gives 1 mg/mL. Lysozyme at absorbance 1.32, 1 cm and dilution factor 2 also gives 1 mg/mL.
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Frequently asked questions
Can I use the BSA coefficient for any protein?
No. UV absorption depends strongly on sequence and other chromophores. Use a measured or sequence-derived coefficient for the actual sample.
Does the result include dilution correction?
Yes. It reports original-sample concentration. Set the dilution factor to one if you want the measured solution concentration.
What if I only know a molar extinction coefficient?
Choose the molar option and supply molecular weight in g/mol. Check the wavelength, solvent and units against the coefficient source.