Beer-Lambert Law Calculator

Calculate absorbance, concentration, extinction coefficient, or path length using the Beer-Lambert equation

A = ε × c × l
A = Absorbance (no units)
ε = Molar extinction coefficient (M⁻¹cm⁻¹)
c = Concentration (M)
l = Path length (cm)

Input Values

nm

Result

0.000e+0
()

Additional Information

Calculation: A = ε × c × l

Values used:
ε = 0 M⁻¹cm⁻¹
c = 0 M
l = 1 cm

Beer-Lambert Law

The Beer-Lambert law relates the attenuation of light to the properties of the material through which the light is traveling. It's fundamental to spectrophotometry and analytical chemistry.

Common Applications

  • Protein concentration (A280)
  • DNA/RNA quantification (A260)
  • Enzyme kinetics
  • Chemical analysis
  • Drug concentration
  • Environmental monitoring

Typical ε Values

  • DNA (260 nm): ~50 µg/mL per OD
  • RNA (260 nm): ~40 µg/mL per OD
  • Protein (280 nm): Variable
  • NADH (340 nm): 6,220 M⁻¹cm⁻¹
  • BSA (280 nm): 43,824 M⁻¹cm⁻¹

Limitations

  • Valid for dilute solutions (<0.01 M)
  • Assumes no scattering
  • Linear relationship breaks at high concentrations
  • Temperature dependent
  • pH can affect ε values

Tips for Accuracy

  • Keep absorbance between 0.1-1.0
  • Use matched cuvettes
  • Blank with appropriate solvent
  • Consider temperature effects
  • Check for bubbles

FAQ

Q: Why is path length usually 1 cm?
A: Standard cuvettes have 1 cm path length, making calculations simpler.

Q: What units should I use?
A: Use consistent units. Standard is M for concentration and cm for path length.