To see folder sizes instantly in Windows, you must use a third-party disk analyzer like UniDirsize (or alternatives like TreeSize and WizTree), as Windows File Explorer cannot calculate or display total folder sizes within its default directory columns.
Microsoft intentionally omitted this feature from File Explorer for performance reasons. Calculating the size of every folder requires recursively scanning thousands of subdirectories and files in real-time, which would cause severe processor lag and slow your system down. How the Tools Compare Windows File Explorer UniDirsize / Dedicated Disk Analyzers Instant Folder Sizes No (Column remains empty) Yes (Fully populates instantly) System Performance High (Saves CPU cycles) Variable (Scans fast without background lag) Detailed Visualization Yes (Percentage bars, maps, and file counts) Sorting by Size Files only (Folders stay mixed) Yes (Sorts folders from largest to smallest) Windows File Explorer: The Slow, Native Workarounds
If you choose not to download third-party software, File Explorer requires manual actions to see folder sizes: