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Beer–Lambert Law Calculator

Use this Beer–Lambert Law Calculator to compute light absorbance and transmittance of a solution based on its molar absorptivity, concentration, and path length. Ideal for students, chemists, and lab technicians, this tool simplifies spectrophotometric calculations using standard units.

Beer–Lambert Absorbance & Transmittance Calculator

Input Fields
If enabled, the result will update automatically when you change any value.

Absorbance and Transmittance Formula Explained

Formula
\[A = \varepsilon \cdot c \cdot l \]\[T = 10^{-A} \cdot 100 \]

Where:

  • $$A$$ = Absorbance (unitless)
  • $$\varepsilon$$ = Molar absorptivity (L/mol·cm)
  • $$c$$ = Concentration (mol/L)
  • $$l$$ = Path length (cm)
  • $$T$$ = Transmittance (%)


The Beer–Lambert Law describes the linear relationship between the absorbance of light and the properties of the material through which the light passes. This calculator is useful in spectrophotometry to determine the concentration of a substance in a solution by measuring how much light it absorbs. By inputting the molar absorptivity, sample concentration, and path length, you can instantly calculate absorbance and determine the percent transmittance. The results are suitable for laboratory analysis, chemistry education, and quality control applications.

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