Beer-Lambert Calculator
Solve the Beer-Lambert law for absorbance or concentration — enter molar absorptivity, path length, and the known value for an instant result.
The Beer-Lambert law states that, at a selected wavelength, a species’ absorbance is directly proportional to its concentration and the path length of the sample cell: A = εlc, where ε is the molar absorptivity, l is the path length, and c is the concentration.
This calculator solves either direction of the relationship — enter molar absorptivity, path length, and concentration to calculate absorbance (rounded to three decimal places, matching typical spectrophotometer display resolution), or enter absorbance, molar absorptivity, and path length to solve for concentration (rounded to three significant figures).
For a deeper look at where this proportionality breaks down at higher concentrations, see Beer-Lambert Spectroscopic Absorbance Principle.
Enter values above to see your result.