Beer-Lambert Law Calculator
Absorbance, concentration and path length.
Enter your values
Enter the absorbance you are working with.
Enter the molar absorptivity in M⁻¹cm⁻¹.
Enter the path length in cm.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Concentration
- 7.3810e-5 M
- In micromolar
- 73.81
- Transmittance
- 23.99%
- Absorbance
- 0.62
Quick answer
Absorbance is proportional to concentration and path length via molar absorptivity.
A = ε × l × c
At a glance
| What it does | Absorbance, concentration and path length. |
|---|---|
| Category | Science |
| Inputs needed | Absorbance, Molar absorptivity, Path length |
| Main output | Concentration |
| Formula | A = ε × l × c |
| Cost | Free — no sign-up, no download |
How to use the Beer-Lambert Law Calculator
- 1Enter the measured absorbance.
- 2Enter molar absorptivity for the analyte and wavelength.
- 3Enter the cuvette path length.
Inputs explained
- Absorbance
- Enter the absorbance you are working with.
- Molar absorptivity(M⁻¹cm⁻¹)
- Enter the molar absorptivity in M⁻¹cm⁻¹.
- Path length(cm)
- Enter the path length in cm.
Worked example
Using the values the calculator loads with:
Inputs
- Absorbance0.62
- Molar absorptivity8400 M⁻¹cm⁻¹
- Path length1 cm
Results
- Concentration7.3810e-5 M
- In micromolar73.81
- Transmittance23.99%
- Absorbance0.62
Frequently asked questions
What absorbance range is reliable?
0.1–1.0 — outside that, detectors lose linearity.
Why is transmittance shown?
Some instruments report %T rather than absorbance.
What do I need to enter into the Beer-Lambert Law Calculator?
Just 3 values: absorbance, molar absorptivity, path length. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Beer-Lambert Law Calculator work out the answer?
Absorbance is proportional to concentration and path length via molar absorptivity. It applies the formula A = ε × l × c and shows the working so you can check each step by hand.
Is the Beer-Lambert Law Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.