Extinction Coefficient Calculator

Determine protein concentration from UV absorbance (A280).

Absorbance (A280)

Extinction Coeff (ε) M⁻¹cm⁻¹

Path Length (l) cm

Molecular Weight (kDa) *Optional

Molarity

0.00e0 M

Concentration

0.00 mg/mL

The Beer-Lambert Law

The Beer-Lambert law states that the quantity of light absorbed by a substance dissolved in a fully transmitting solvent is directly proportional to the concentration of the substance and the path length of the light through the solution. At 280 nm, tryptophan and tyrosine residues are the primary light absorbers in proteins.

Formula used: A = ε * c * l
c (Molar) = A / (ε * l)
c (mg/mL) = c (Molar) * MW (g/mol)

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