Beer-Lambert Law Calculator
Solve absorbance, molar absorptivity, path length or concentration and inspect ideal transmittance.
What would you like to do next?
Relate absorbance to concentration and optical path length
Select the unknown, then enter absorbance, molar absorptivity, path length and concentration in the displayed units. The calculator rearranges the Beer-Lambert relationship and reports ideal percent transmittance as a second check on absorbance. Keeping the coefficient, path and concentration product visible helps users audit unit choices and identify which factor drove a result.
Validate the linear range with standards
Real measurements depend on wavelength selection, blank correction, instrument response and sample behavior. Stray light, scattering, chemical association and high concentration can break linear proportionality. Build and review an appropriate calibration curve, use matched cells and follow the instrument method when converting an unknown laboratory sample into a reported concentration.
Frequently asked questions
Which path-length unit is used?
Enter optical path length in centimeters with molar absorptivity in liters per mole-centimeter.
How is transmittance derived?
Ideal decimal transmittance is ten raised to negative absorbance, then converted to percent.
Does the result prove linear response?
No. Verify the working range with standards and the actual instrument method.