It seems this has been a bug many have been seeing occur since the 1803 drop of Windows 10 last year. Affecting quite a few users, Windows 10 may sometimes run into an issue where it begins to report incorrect directory and file sizes. Sometimes it could be when you check the properties of a folder, a sub-folder, or a group of files.
Windows users have been reporting this to Microsoft since the release of the 1803 port of Windows 10, however there is yet to be a hard solution to fixing the problem. Microsoft has not responded either outside of a few unofficial mentions that the best way to circumvent the bug, is to limit your directory trees/paths to no more than 260 characters (path to file + file name). However, this solution does not work for everyone experiencing the problem, and for some, their character count doesn’t even make it that far to begin with.
We noticed that we were able to reproduce the issue on a few different machines and one laptop, when searching through large archives stored on these machines. Sure enough, some directories would report back as being within the MB’s, when the files and subfolders inside added into the GB’s in reality. In some cases, it would be the other way around. We found 7 files that would report back as 98GB in size (that’s nearly 1TB) when they are all selected together and the properties screen is brought up from the right-click menu. The actual size of the files add up to 1,011MB (or around 1GB). The character count of the directory path (with spaces) is only 105, with the files being an extra 6-20 characters.
To make things worse, most of the machines here have software actively running on them that monitors various health aspects of the system. One of these items is hard drive health, used as an attempt to measure the life expectancy of a drive to help clone and replace it before it might completely fail. Programs like Acronis Drive Monitor and CrystalDiskInfo. One of the machines affected by this bug had the software running, which was triggered into a critical error claiming that the drive is about to die. Placing the drive into a machine not affected by this bug in Windows resulted in a 100% bill of health for the drive.
Which means this bug can not only cause confusion in Windows 10 users (for example, some users report deleting the wrong folders when cleaning out their system because Windows reported the directory as empty or close to it, when it actually contained a large collection of sensitive information like family photos), but it can also confuse other applications and services that the user (or an organization) depends on for making important and potential costly choices.
So hopefully this bug is high on Microsoft’s radar for future releases as it seems to be affecting far too many users to be placed on the backburner. Until then, hopefully, the 260 character limit might work for you.