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Convert A ↔ %T ↔ T with A = −log₁₀(T) and %T = 100·T; returns all three representations for spectrophotometry work.
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Fill in the form, run the tool, and review the result in one place.
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Tool usage guide
The Absorbance↔Transmittance Converter quickly switches between absorbance (A), percent transmittance (%T), and fractional transmittance (T) using the standard relation A = −log₁₀(T). Designed for spectrophotometry and optical density workflows, it outputs all three corresponding values simultaneously with customizable decimal precision.
Background
A lab researcher measures an OD600 reading of 1.0 for a bacterial culture in a cuvette.
Problem
Determine the exact percentage of light passing through the suspension.
How to use
Enter 1 as the Value, select 'Absorbance (A)' as the Input Quantity, and set Decimal Places to 4.
{"value": 1, "inputQuantity": "absorbance", "decimalPlaces": 4}Outcome
Returns T = 0.1 and %T = 10%, confirming 10% light transmission.
Background
A technician calibrating a spectrometer uses a neutral-density standard rated at 50% transmittance.
Problem
Calculate the expected absorbance value to verify instrument calibration.
How to use
Enter 50 as the Value, select 'Transmittance (%T)' as the Input Quantity, and set Decimal Places to 3.
The tool uses A = −log₁₀(T), T = 10⁻ᴬ, and %T = 100 · T (or A = 2 − log₁₀(%T)).
An absorbance (A) of 1.0 corresponds to a transmittance fraction of 0.1, meaning exactly 10% of incident light passes through.
In standard absorption spectroscopy, transmitted light cannot exceed incident light (100% or T = 1.0), and negative transmittance is physically impossible.
Yes, choose 'Transmittance (T, 0–1)' as your input quantity to enter fractions such as 0.5 directly.
You can set the output precision anywhere from 0 up to 8 decimal places.
{"value": 50, "inputQuantity": "percentTransmittance", "decimalPlaces": 3}Outcome
Returns A = 0.301 and fractional transmittance T = 0.5.