Beer-Lambert Law Calculator

Calculate concentration from absorbance using the Beer-Lambert law (A = εlc). Also computes transmittance.

Absorbance (A)

Molar Absorptivity (ε)

Path Length (cm)

Tab to move between fields

Concentration

0 M

% Transmittance

31.62%

Concentration0.076 mM

Concentration75.76 µM

Transmittance (T)0.3162

How to Use This Calculator

Enter Absorbance (A), Molar Absorptivity (ε), and Path Length (cm).
Review Concentration (M) and % Transmittance.
Use Concentration (mM) and Concentration (µM) to inform your decision.
Use the chart to visualize the results and explore different scenarios by adjusting inputs.

What each input means

Absorbance (A): Measured absorbance (unitless). Reliable range is typically 0.1–1.0.
Molar Absorptivity (ε): Molar extinction coefficient in L/(mol·cm). Example: dsDNA at 260nm ≈ 6600.
Path Length (cm): Cuvette path length in centimeters. Standard cuvettes are 1 cm.

A = εlc → c = A / (ε × l)

Identify Input Parameters
Absorbance (A) = 0.5, Molar Absorptivity (ε) = 6600, Path Length (cm) = 1 = 3 input(s) provided
Calculate Concentration
Concentration = c
0.000075758 = 0.000075758
Calculate % Transmittance
% Transmittance
31.62 = 31.62
Calculate Concentration
Concentration
0.076 = 0.076
Calculate Concentration
Concentration
75.76 = 75.76

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