Beer Lambert Law Calculator W Formula


The Beer-Lambert Law, also known as the Beer-Lambert-Bouguer law, is a fundamental principle in spectroscopy and photometry used to relate the absorption of light to the properties of the material through which the light is traveling. This law provides a quantitative relationship between the concentration of an absorbing species in a solution, the path length of the light through the solution, and the absorbance of the solution at a particular wavelength.

How to Use

To use the Beer-Lambert Law calculator, simply input the values for concentration (C), molar absorptivity (ε), and path length (l) into the respective fields. Then click on the “Calculate” button to obtain the absorbance (A) value.


The Beer-Lambert Law is expressed by the formula:



  • A = Absorbance
  • ε = Molar absorptivity (extinction coefficient)
  • l = Path length of the sample
  • C = Concentration of the absorbing species

Example Solve

Let’s say we have a solution with a concentration of 0.05 M, a path length of 1 cm, and a molar absorptivity of 300 L/(mol·cm). Using the Beer-Lambert Law formula:


So, the absorbance (A) of the solution is 15.


Q: What is the significance of the Beer-Lambert Law in spectroscopy?
A: The Beer-Lambert Law provides a quantitative relationship between the concentration of an absorbing species in a solution and the absorbance of the solution, making it a crucial tool in determining concentration levels in various chemical analyses.

Q: How does the path length affect absorbance?
A: The longer the path length, the greater the absorbance, as more light interacts with the absorbing species, leading to increased attenuation.

Q: Can the Beer-Lambert Law be applied to all solutions?
A: While the Beer-Lambert Law is widely applicable, it assumes that the absorbing species is uniformly distributed throughout the sample and that the incident light is monochromatic. Deviations from these conditions may lead to inaccuracies.


The Beer-Lambert Law serves as a cornerstone in quantitative spectroscopic analysis, providing a straightforward means to determine the concentration of absorbing species in a solution. By understanding and applying this fundamental principle, researchers across various fields can derive valuable insights into the properties of materials.

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