Beer-Lambert Law & Spectrophotometry Calculator
Computes optical absorbance, percent transmittance, molar extinction coefficient, cuvette path length, and chemical concentration using the Beer-Lambert Law (A = ε·b·c) with an interactive calibration curve SVG.
Beer-Lambert Law & Spectrophotometry Calculator
Calculate absorbance (A), molar absorptivity (ε), cuvette path length (b), or concentration (c) with calibration plot
What is the Beer-Lambert Law?
The Beer-Lambert Law (or Beer's Law) relates the attenuation of light through a substance to the properties of that substance in UV-Vis spectrophotometry.
It establishes that optical absorbance (A) is directly proportional to the molar absorptivity coefficient (ε), the optical path length (b), and the molar concentration of the absorbing solute (c).
Formula & Step-by-Step Calculation
Linear relation between absorbance A, molar extinction coefficient ε (L/(mol·cm)), path length b (cm), and concentration c (mol/L).
Worked Step-by-Step Examples
Calculate absorbance for a solution with ε = 8400 L/(mol·cm), b = 1.0 cm, c = 1.5 × 10⁻⁴ mol/L
Common Real-World & Academic Use Cases
- ✓ UV-Vis spectrophotometry quantification in analytical chemistry
- ✓ Protein and nucleic acid concentration assays (A260 / A280)
- ✓ Enzyme kinetics optical density time-course tracking
- ✓ Environmental water pollutant optical assays
How to Use the Beer-Lambert Law & Spectrophotometry Calculator
Select Solve Variable
Choose to solve for Absorbance (A), Concentration (c), Molar Absorptivity (ε), or Path Length (b).
Input Known Parameters
Enter known values with appropriate units (e.g. standard 1.0 cm cuvette path length).
Inspect Calibration Curve
View the interactive Beer's Law standard curve SVG showing sample placement along the linear dynamic range.
Frequently Asked Questions
Q: Why does Beer's Law deviate from linearity at high concentrations?
At high concentrations (usually A > 1.5 - 2.0), electrostatic interactions between solute molecules, refractive index changes, and stray light in the spectrophotometer cause non-linear deviations.