Beer-Lambert Law Calculator Formula
Understand the math behind the beer-lambert law calculator. Each variable explained with a worked example.
Formulas Used
Absorbance (A)
absorbance = molar_absorptivity * path_length * concentrationPercent Transmittance (%T)
transmittance = pow(10, -molar_absorptivity * path_length * concentration) * 100Variables
| Variable | Description | Default |
|---|---|---|
molar_absorptivity | Molar Absorptivity (epsilon)(L/(mol·cm)) | 6220 |
path_length | Path Length (l)(cm) | 1 |
concentration | Concentration (c)(M) | 0.0005 |
How It Works
Beer-Lambert Law
The Beer-Lambert law relates the absorbance of a solution to the concentration of the absorbing species, the path length, and the molar absorptivity.
Formula
A = epsilon × l × c
where A is absorbance (dimensionless), epsilon is the molar absorptivity (L/(mol·cm)), l is the optical path length (cm), and c is the molar concentration (mol/L). Transmittance: T = 10^(-A).
Worked Example
NADH in a 1 cm cuvette at 0.5 mM concentration (epsilon = 6220 at 340 nm).
molar_absorptivity = 6220path_length = 1concentration = 0.0005
- 01A = 6220 × 1 × 0.0005 = 3.110
- 02%T = 10^(-3.110) × 100 = 0.0776 × 100 = 7.76%
Ready to run the numbers?
Open Beer-Lambert Law Calculator