How to use the beer–lambert law calculator
Find concentration from absorbance. Enter absorbance, molar absorptivity, path length in the fields above; the concentration, concentration, transmittance are computed instantly and plotted on the chart so you can see how the answer changes.
Formula
Variables
- A — Absorbance
- e — Molar absorptivity (L/(mol·cm))
- l — Path length (cm)
Worked example
With absorbance = 0.45, molar absorptivity = 6220 L/(mol·cm), path length = 1 cm, the calculator gives concentration ≈ 7.2347 × 10⁻⁵ mol/L; concentration ≈ 72.34727 µM; transmittance ≈ 35.48134 %.
Frequently asked questions
What is the formula for the beer–lambert law calculation?
Concentration (mol/L) = A / (e × l). Concentration (µM) = [Concentration] × 1e6. Transmittance (%) = 100 × 10^(-A). Here A is absorbance, e is molar absorptivity (L/(mol·cm)), l is path length (cm).
What inputs do I need for the beer–lambert law calculator?
You need absorbance, molar absorptivity in L/(mol·cm), path length in cm. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use this calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.