The good thing about it being introduced by a Windows Update is that Microsoft will most likely release a fix in the next couple of updates.

That’s why you might also notice that your drive size isn’t correct either. This is what leads to this unexpected file sizes. This bug prevents the File Explorer to read the metadata of a file correctly. This is a known bug in the Windows 10 that was introduced in one of the latest Windows Updates. Any folder can be affected by this incorrect folder size issue. This incorrect folder size problem isn’t specific to a certain drive or certain types of folders. If you rename the folder then the size will change but it still won’t be the correct size. Some users saw the folder size of 4TB as well. It will most likely be a random number and it can be a bigger or smaller number than the actual size. For example, if you have a folder with 100 GB of data and you check its size via the properties then you might see a wrong size there. When Folder Size detects that other programs are doing a lot of reading to and writing from the hard disk being scanned, the background scanning will wait for the other programs to finish.If you are a Windows 10 user then you might experience the issue with the Windows folder sizes. Background scans won't monopolize your disk.Explorer will automatically update the folder size column in real-time.Large folders will continue to scan in the background while you browse your folders. As soon as you display the Folder Size column, you'll see sizes immediately. No scanning phase before you can start.Not just for disk cleanup, but for any time you need to choose a folder. It's always there when you're viewing your folders (even in Open and Save file dialog boxes, you can change the view), and it's a great visual cue to help you find the one you're looking for. Don't switch to another program to see folder sizes.It keeps track of which folders you view, and scans them in the background so you can see complete size of all files within the folder.

The new column shows not only the size of files, but also the size of folders. Folder Size for Windows adds a new column to the Details view in Windows Explorer.

Folder size app windows 10