What this calculator does
Beer–Lambert law (absorbance) works out absorbance and transmittance of a solution from its concentration. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
FormulaA = ε·c·l; %T = 10^−A × 100
The inputs explained
| Field | What to enter |
|---|---|
| Molar absorptivity ε (L/(mol·cm)) | A number, measured in L/(mol·cm). Starts at 1000. |
| Concentration (mol/L) | A number, measured in mol/L. Starts at 0.001. |
| Path length (cm) | A number, measured in cm. Starts at 1. |
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the answer changes with molar absorptivity ε
Every other input is held at the calculator’s starting values while molar absorptivity ε varies. Select any row to load that scenario into the calculator.