Beer-Lambert Law UV-Vis Absorbance, Transmittance & Concentration Calculator

Convert UV-Vis optical absorbance (OD) into micromolar concentration and %T.

Sample Concentration (Micromolar)
24.29 μM
Percent Optical Transmittance (%T) 20.89 %
Concentration in Millimolar (mM) 0.02 mM
Light Absorbed Fraction 79.11 %
Inputs
AU
Measured optical absorbance (A, dimensionless OD units).
M⁻¹·cm⁻¹
Molar absorptivity ε in M⁻¹·cm⁻¹.
cm
Optical cuvette pathlength (l) in centimeters (1.0 cm standard).
Results & Graph
Sample Concentration (Micromolar)
24.29 μM
Percent Optical Transmittance (%T)
20.89 %
Concentration in Millimolar (mM)
0.02 mM
Light Absorbed Fraction
79.11 %

Sample Concentration (Micromolar)

Graph 1 • Measured Absorbance Od Sensitivity Recalculates the domain equation across 50% to 150% of the primary input while holding other parameters constant.
0 μM 19.7 μM 39.3 μM 50%: 12.14 μM 12.1 50% 75%: 18.21 μM 18.2 75% 100%: 24.29 μM 24.3 100% 125%: 30.36 μM 30.4 125% 150%: 36.43 μM 36.4 150%
Graph 2 • Primary & Supporting Metric Comparison Compares the primary output alongside supporting domain benchmarks.
Sample Concentration (Micromolar) 24.29 μM Percent Optical Transmittance (%T) 20.89 % Concentration in Millimolar (mM) 0.02 mM Light Absorbed Fraction 79.11 %
Graph 3 • Exact Output Table & Units Displays each calculated output in its exact domain unit.
Sample Concentration (Micromolar)24.29 μMPercent Optical Transmittance (%T)20.89 %Concentration in Millimolar (mM)0.02 mMLight Absorbed Fraction79.11 %
Summary: An absorbance of 0.68 AU across a 1 cm pathlength (ε=28,000 M⁻¹·cm⁻¹) corresponds to 24.29 μM and 20.89% transmittance.
Summary: An absorbance of 0.68 AU across a 1 cm pathlength (ε=28,000 M⁻¹·cm⁻¹) corresponds to 24.29 μM and 20.89% transmittance.
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Formula & Mathematical Methodology: Beer-Lambert Absorbance Reference Equation

A = ε × l × c ⇒ c = A / (ε × l)
%Transmittance = 102 − A
A = ε × l × c ⇒ c = A / (ε × l); %Transmittance = 10^(2 − A)
  • measuredAbsorbanceOd: Measured Absorbance Od (AU)
  • molarExtinctionEpsilon: Molar Extinction Epsilon (M⁻¹·cm⁻¹)
  • pathlengthCm: Pathlength Cm (cm)

Rounding: Laboratory and clinical equations retain full floating-point precision and round displayed results to 2 decimal places.

Worked Example: Reference Calculation: Beer-Lambert Absorbance

Convert UV-Vis optical absorbance (OD) into micromolar concentration and %T.

  1. Enter the reagent concentrations, assay readings, or clinical laboratory parameters.
  2. Compute the standard formula: A = ε × l × c ⇒ c = A / (ε × l); %Transmittance = 10^(2 − A).
  3. Review the primary result, supporting reference intervals, and 3 SVG visualizations.
Result: Evaluates Beer-Lambert Absorbance via A = ε × l × c ⇒ c = A / (ε × l); %Transmittance = 10^(2 − A).

Frequently Asked Questions

What formula is used by the Beer-Lambert Law UV-Vis Absorbance, Transmittance & Concentration Calculator?

It computes A = ε × l × c ⇒ c = A / (ε × l); %Transmittance = 10^(2 − A) and plots three custom SVG graphs showing parameter sensitivity and component breakdowns.

Can I compare different reagent dilutions or lab scenarios side by side?

Yes. Use the "Compare (0/3)" button to pin up to 3 scenarios side by side.

Are entered values stored on any server?

No. Every calculation runs 100% locally in your browser.

Science & Engineering · Analytical Chemistry & Lab Bench

Beer-Lambert Law UV-Vis Absorbance, Transmittance & Concentration Calculator: inputs, method, and how to read the result

Convert UV-Vis optical absorbance (OD) into micromolar concentration and %T.

Choose inputs for the case you are checking

The defaults are illustrative. Replace them with values for your case and keep the units shown beside each field.

  • Measured Absorbance Od: Measured optical absorbance (A, dimensionless OD units).
  • Molar Extinction Epsilon: Molar absorptivity ε in M⁻¹·cm⁻¹.
  • Pathlength Cm: Optical cuvette pathlength (l) in centimeters (1.0 cm standard).

What the calculation includes

With the default values shown, Sample Concentration (Micromolar) is 24.29 μM. The calculation follows Beer-Lambert Absorbance Reference Equation; the formula and variable definitions above show how the inputs combine.

One-input check: With the other defaults held constant, changing Measured Absorbance Od from 0.68 AU to 0.75 AU changes Sample Concentration (Micromolar) from 24.29 μM to 26.79 μM. This is a comparison inside the calculator's stated model, not a prediction.

Where to use caution

  • Uses standard IUPAC atomic weights, 25°C (298.15 K) reference thermodynamics, and published clinical literature equations.
  • Educational and laboratory reference tool only; clinical scoring calculators do not replace professional medical judgment or institutional protocols.

Scope: IUPAC / NIH Laboratory & Clinical Reference Standard Check the assumptions and limitations against your situation before relying on the estimate.

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