absorbance.Open workbench
Learn/ The visual explainer

A little less light. A little more insight.

Change the concentration or the distance light travels. See how an idealised sample changes the transmitted light.

Explore the relationship

L·mol⁻¹·cm⁻¹ · A teaching value, not a coefficient for a real substance.
What happens if…
Light through a sampleIdealised model
An incident beam passes through an idealised sample. The transmitted intensity is calculated from absorbance.path length · 1 cmINCIDENT LIGHTTRANSMITTED100%31.62%
Absorbance · dimensionless0.5
Percentage transmittance31.62%
A = ε × l × c
%T = 100 × 10⁻ᴬ

Idealised model at a selected wavelength. Beam intensity is illustrative; this graphic does not predict a solution’s perceived colour.

View model values as a table
Current model inputs and calculated outputs

Double the concentration. Not the darkness.

At a fixed path length and coefficient, doubling concentration doubles absorbance. Transmittance changes logarithmically: A = 1 means 10% transmittance, while A = 2 means 1%.

Doubling path length has the same effect on absorbance in this model. The calculated transmitted fraction controls the outgoing beam’s opacity.

Real measurements need context

The coefficient is specific to wavelength, substance and conditions. Scattering, chemical changes or instrument limitations can make this model unsuitable. No spectra or empirical measurements are generated here.

Read the IUPAC definition ↗