Undup

Sure enough you can view the size of a folder through the default properties panel, but it can become a time-consuming operation if you want to analyze the size of multiple directories, since there’s no option to view size of directories in an explorer window. Luckily, you can rely on applications like Undup for this kind of task.

Select and scan directories of interest

You’re first taken through a setup process to ensure the proper functionality of the application. Note, however, that it completely relies on .NET Framework, so you need to make sure it’s on your computer. On the other hand, it’s usually bundled inside the default set of features with modern Windows iterations.
Just so you don’t end up waiting too much time, the application lets you select directories or drives to scan in case you don’t want an overview of your entire system. This is done in a new window, fitted with a browse dialog to easily pick a directory of interest. Label name and total volume size are displayed.

Cool representation of size distribution and duplicates

It can take a little while to scan the directory of interest, but this mostly depends on the size of the source. It’s possible to add multiple directories to the list to have them ready for analysis at any given moment. The list shows the name of the drive, the path, label, as well as the total size.
Selecting an item of interest and choosing to show size values brings up a new window. On the bright side of things, visualization is neatly represented in differently-sized squares, with exact values displayed on mouseover. More than that, duplicate items are shown in color, just so you know whether or not they take up space for no reason.

In conclusion

Taking everything into consideration, we can state that Undup is a practical application with which you can analyze the size distribution of entire drives. It offers a neat representation of space, while also displaying possible duplicate items to help you free up some space.