WinDirStat is not available for Android but there are a few alternatives with similar functionality. The best Android alternative is DiskUsage, which is both free and Open Source. If that doesn't work for you, our users have ranked more than 50 alternatives to WinDirStat, but unfortunately only two of them are available for Android. If you can't find an alternative you can try to filter for web or SaaS options.
DiskUsage provides a way to find out which files and directories on the SD card of your Android phone are consuming the most space. It displays diagram with directories/subdirectories proportional to their size. Users are allowed to zoom in to look at specific directory content.
DiskUsage vs WinDirStat opinions
Almost everyone thinks DiskUsage is a great alternative to WinDirStat.
Because it has functions simular to WinDirStat and it's for Android!
Grid Size file manager has all the functionality you expect from a file manager with a useful visual feature. The grid view graphically displays the contents of your storage drive proportional to the size of each folder and file.