Why does the 'Percent of parent' column show 100% for a drive root?

Question / Problem

I currently use about half of the capacity of my local drive, so half of it is free. TreeSize still shows 100% in the 'Percent of parent column'. Why doesn't it show 50%?

Answer / Solution

The percent values in TreeSize are defined to be based on the accessible and filtered sizes - so basically to the size values also shown in the related columns (depending on the current view mode: size, allocated space, or number of files).

Using the capacity of a drive instead would break this definition and even be undefined for many usecases (What's the number of unused files on a drive? How to interprete filtered results? How to calculate the capacity of a subfolder? ...)

The capacity and free space of a drive are represented as their own piece of information in the statusbar instead and can be shown as a separate tile with the treemap chart instead.