Beer–Lambert Law Calculator
🔥 Thermochemistry & Bonding. Use the Beer–Lambert law formula to find absorbance, molar absorptivity ε, concentration, path length: pick the value you want, type the others, and the answer updates as you go.
Pick the ○ next to the value you want to find, fill in the others, and it solves as you type.
What each letter means
| Quantity | Unit |
|---|---|
| Absorbance | no unit |
| Molar absorptivity ε | L/(mol·cm) |
| Concentration | mol/L |
| Path length | cm |
Worked example
Find the absorbance when Molar absorptivity ε = 5000 L/(mol·cm), Concentration = 1 × 10⁻⁴ mol/L, Path length = 1 cm.
Using A = ε c l: Absorbance = 0.5.
Frequently asked questions
What is the formula for Beer–Lambert law?
A = ε c l.
What do the letters stand for, and what units are used?
Absorbance, Molar absorptivity ε in L/(mol·cm), Concentration in mol/L, Path length in cm.
How do you calculate absorbance?
Put the values into A = ε c l. For example, with Molar absorptivity ε = 5000 L/(mol·cm), Concentration = 1 × 10⁻⁴ mol/L, Path length = 1 cm, absorbance = 0.5.
Can I solve for a different value?
Yes. In the calculator above, pick the circle next to any value (absorbance, molar absorptivity ε, concentration, path length) and fill in the others: it rearranges the formula for you.
