Optical Density Calculator | OD vs Absorbance Explained

Calculate Optical Density (OD) from Percent Transmittance

Enter the percentage of light that passes through the sample (0-100%).

Use our free Optical Density Calculator to quickly convert Percent Transmittance (%T) to Optical Density (OD) and Absorbance (A). Understand the crucial difference and relationship between OD and Absorbance, explore the underlying formulas, and learn their applications in spectrophotometry. Get precise results for your scientific experiments and analyses.

Formula:

The fundamental relationship between Optical Density (OD), also known as Absorbance (A), and Transmittance (T) is given by:

OD = A = -log10(T)

Where:

  • OD = Optical Density (unitless)
  • A = Absorbance (unitless)
  • T = Transmittance (as a decimal, e.g., 0.5 for 50%)
This calculator uses Percent Transmittance (%T) as input, where T = %T / 100.

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