How to use the absorbance and transmittance calculator
Convert between percent transmittance and absorbance. Enter transmittance in the field above; the absorbance is computed instantly and plotted on the chart so you can see how the answer changes.
Formula
Variables
- T — Transmittance (%)
Worked example
With transmittance = 25 %, the calculator gives absorbance ≈ 0.60206.
Frequently asked questions
What is the formula for the absorbance and transmittance calculation?
Absorbance = 2-log10(T). Here T is transmittance (%).
What inputs do I need for the absorbance and transmittance converter calculator?
You need transmittance in %. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use this calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.