Free Beer-Lambert Law Calculator

Calculate absorbance, concentration, or path length using the Beer-Lambert law for spectrophotometry.

L/(mol·cm)
cm
M

Absorbance (A)

3.1100

Percent Transmittance (%T)0.08 %

Absorbance (A) vs Molar Absorptivity (epsilon)

Beer-Lambert Law

The Beer-Lambert law relates the absorbance of a solution to the concentration of the absorbing species, the path length, and the molar absorptivity.

Formula

A = epsilon × l × c

where A is absorbance (dimensionless), epsilon is the molar absorptivity (L/(mol·cm)), l is the optical path length (cm), and c is the molar concentration (mol/L). Transmittance: T = 10^(-A).

Example Calculation

NADH in a 1 cm cuvette at 0.5 mM concentration (epsilon = 6220 at 340 nm).

  1. 01A = 6220 × 1 × 0.0005 = 3.110
  2. 02%T = 10^(-3.110) × 100 = 0.0776 × 100 = 7.76%

Frequently Asked Questions

Learn More

Understanding Molarity

Learn what molarity is, how to calculate it, and why it matters in chemistry. Covers moles, liters, dilution, and step-by-step examples for preparing solutions.

Related Calculators