Lambert-Beer Law Calculator

Calcolatore Legge di Lambert–Beer

Unità predefinite: ε in L·mol⁻¹·cm⁻¹, l in cm, c in mol·L⁻¹ (M). Formule: A = ε·l·c, T = 10−A, %T = 100·T.

Impostazioni
L’app non converte le unità di ε: assicurati coerenza con l e c.
A) Assorbanza da ε, l, c
B) Risolvi per l’incognita
C) Curva di calibrazione (A = m·c + b)
Stima m e b
Oppure incolla coppie c,A (una per riga) per regressione lineare:
D) Diluizione (C₁V₁ = C₂V₂)
Assunzioni: soluzioni diluite, cammino ottico costante, assenza di effetti chimici/fisici (scattering, fluorescenza, reazioni).
Per concentrazioni elevate la linearità può non valere (deviazioni dalla legge).

The Absorbance Calculator by UtileApp lets you instantly compute absorbance (A), transmittance (T), and concentration (c) using the Beer–Lambert law: A=ε⋅l⋅cA = varepsilon cdot l cdot cA=ε⋅l⋅c

It also handles calibration curves (linear, A=mc+bA = m c + bA=mc+b) and dilution equations (C1V1=C2V2C_1 V_1 = C_2 V_2C1​V1​=C2​V2​), allowing you to go from raw absorbance data to the final sample concentration with ease.

Main features

  • Direct calculation of A, T, and %T from known values of ε (molar absorptivity), path length (l), and concentration (c).
  • Reverse solving: determine any missing parameter — ε, l, c, or A — from the others.
  • Calibration curve module:
    • Compute concentration (c) from absorbance (A) using known m and b.
    • Estimate m and b from two standard points or by linear regression over multiple data points (with R²).
  • Dilution module: use C1V1=C2V2C_1V_1 = C_2V_2C1​V1​=C2​V2​ to correct for stock and working solution differences.
  • Linearity guidance: automatic warnings if absorbance is too high or too low.
  • Adjustable precision: customize decimal places and output units.

Use and benefits

Perfect for UV–Vis spectrophotometry, both in educational and laboratory environments, this calculator minimizes unit and transcription errors while providing clear, immediate results. It’s ideal for quantitative analysis, standard curve generation, and dilution corrections.

Example calculations

  • Given ε = 1.5×10⁴ L·mol⁻¹·cm⁻¹, l = 1 cm, c = 2.0×10⁻⁵ M →
    A ≈ 0.300, %T ≈ 50%.
  • From two calibration standards (c₁, A₁), (c₂, A₂) → find slope (m), intercept (b), and then the unknown sample concentration from its A.

Notes

  • Assumes dilute solutions, constant path length, and absence of non-ideal effects (e.g., scattering, fluorescence, chemical interference).
  • Units of ε must be consistent with l (cm) and c (mol·L⁻¹).