Need the formula describing the relationship between absorbance and %T?

Say input is 1 the output is going to be a fraction of the input if there is any absorption, thus %T. The amount of absorption is given by the above equation. When A = 0; %T = 100. However when we look at the graph there is a vertical line at %T = 0, which means A would be infinite.

Beer's Law - Google Search

By input I mean a light ray passing through something.