Free Chemistry Calculator

Beer–Lambert Law Calculator

Solve one missing quantity in the Beer–Lambert relationship for a single absorbing species. Path length is normalized to centimeters and concentration to mol/L before calculation.

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Solve the Beer–Lambert relationship

Select the missing quantity and enter the other three. Molar absorption coefficient is interpreted in L·mol⁻¹·cm⁻¹.

L·mol⁻¹·cm⁻¹
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What is a Beer–Lambert law calculator?

This calculator relates absorbance to molar absorption coefficient, optical path length, and amount concentration for a specified wavelength and species. Prepare or check the solution concentration with the Molarity Calculator.

How does the Beer–Lambert calculator work?

Path length is converted to centimeters and concentration to mol/L. The tool rearranges A = εbc for the selected unknown and converts absorbance to transmittance with T = 10^(−A).

What formula does the Beer–Lambert law use?

A = εbc, where A is decadic absorbance, ε is molar absorption coefficient, b is path length, and c is amount concentration. Percent transmittance = 100 × 10^(−A).

How do you use the Beer–Lambert law calculator?

Select the missing variable, leave its numeric field blank, and enter the other three with units. If a stock is diluted before measurement, use the Dilution Calculator for the modeled final concentration.

What do absorbance and transmittance results mean?

Absorbance is logarithmic; percent transmittance is the fraction of incident radiant power transmitted under the measurement definition. The Scientific Calculator can verify the base-10 exponential conversion.

When can Beer–Lambert results be non-linear?

High concentration, chemical association, scattering, stray light, polychromatic radiation, bandwidth, cuvette mismatch, baseline errors, and wavelength-dependent ε can cause deviations. This calculation does not calibrate an instrument.

Who should use this spectroscopy calculator?

It supports education and preliminary single-species spectrophotometry calculations. Use the Percentage Calculator only to check a reported transmittance share, and follow validated analytical procedures for professional measurements.

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Frequently asked questions about Beer–Lambert Law

It relates decadic absorbance to molar absorption coefficient, path length, and amount concentration through A = εbc.
It is interpreted as liters per mole per centimeter.
Yes. Millimeters and meters are converted to centimeters.
Yes. Concentration is converted to mol/L before calculation.
Transmittance is 10 raised to negative absorbance; percent transmittance multiplies that value by 100.
Yes. An absorbance of zero corresponds to 100% transmittance in the ideal mathematical relationship.
No. Use an experimentally appropriate wavelength and molar absorption coefficient for the specified species and conditions.
No. It performs the equation only and does not correct instrument or sample effects.

Sources and methodology

The calculation method and explanatory context can be checked against these authoritative primary references.

Scope: This free tool supports learning and planning. Confirm important laboratory, academic, medical, environmental, or industrial work with current protocols and qualified review.
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