TreeSize on Windows 11

Q: Is it safe to delete C:\Windows.old on Windows 11?

It's safe once you're confident you won't roll back to the previous Windows version. Use Disk Cleanup's "Clean up system files" option to remove it rather than deleting the folder manually, since Windows keeps file permissions on it that resist a normal delete.

Q: Does scanning a drive interfere with Storage Sense?

No. Scanning only reads folder and file sizes; it doesn't change any settings or delete anything on its own. Storage Sense keeps running on whatever schedule you set for it, independent of any scan you run.

Q: Why does OneDrive show a huge folder that doesn't match my free disk space?

Files-on-demand placeholders report their full cloud size even when unopened, so a folder can look large in a scan while using little real disk space. Right-click a file and check its OneDrive status icon to see whether it's actually downloaded.

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Windows 11 hides most classic context-menu entries behind a Show more options row (or Shift + F10 for the old menu directly). If a disk space analyzer used to add a shortcut to "scan this folder," that entry may now sit one click deeper than you remember, inside the expanded menu instead of the short one Microsoft shows by default.

If you cannot find an added menu entry at all, it is worth opening the program directly and pointing it at the folder from inside its own window rather than hunting through Explorer's menu layers.

Settings > System > Storage isn't a folder scan

Windows 11's Storage page groups space into buckets: Apps, Temporary files, Documents, and so on. It's a decent 30-second overview, but it categorizes by file type, not by folder location, so it cannot tell you that one specific project folder under C:\Users\yourname\Documents is 40 GB by itself.

A folder-tree scan works the opposite way: it doesn't care what kind of file it is, only where it sits and how big it is. That's the view you need once Storage tells you "Documents is large" but not which document folder is the problem. We compare the two approaches in more detail on Windows storage settings vs TreeSize.

Storage Sense, the automatic cleanup toggle on the same Settings page, deletes temp files and empties the recycle bin on a schedule. It runs quietly in the background and will not show you what it's about to remove before it happens, which is the opposite of a scan you read before deciding anything.

Where Windows 11 tends to hide space

Windows Update staging in C:\Windows\SoftwareDistribution — the update files download here before installing. Windows normally clears this after a successful update; a folder that stays large for weeks suggests an update is stuck.
`C:\Windows.old` — appears after a feature update (for example, moving between Windows 11 versions). It's a rollback copy of the previous install and can easily be 15-25 GB. Windows removes it automatically after about ten days, or you can clear it sooner through Disk Cleanup's system files option rather than deleting it by hand.
OneDrive files-on-demand — placeholder files show their full size in a folder scan even when the actual content lives only in the cloud. A folder that reports 50 GB in OneDrive might occupy only a few hundred MB of real disk space if most files are still cloud-only. Check a file's status icon before assuming a OneDrive folder is really taking up local space.
Xbox and game installs — Windows 11's Xbox app and Game Pass titles often live under C:\XboxGames or C:\Program Files\WindowsApps, and a single modern title can be 60-100 GB. These folders are usually easy to spot at the top of a scan once you sort by size.

A sensible cleanup order

Scan the system drive and sort the top-level folders by size before touching anything.
Check C:\Windows.old and update staging first — these are the folders most likely to be pure waste from an already-finished update.
Look at large game installs and uninstall the ones you haven't opened in months.
Review OneDrive or other cloud-sync folders and switch space-hungry ones to files-on-demand instead of always-downloaded.
Only after that, open user folders like Downloads and Documents, where the content is yours to judge.

For a broader walkthrough that includes Storage Sense settings and OneDrive configuration, see freeing up disk space on Windows 11. If you want the general method for locating big files regardless of Windows version, finding large files on Windows compares the built-in tools with a tree scan.

Windows 11 questions

Why does a folder scan show a different size than the Windows 11 Storage page?

Storage groups files by category across the whole drive, while a folder scan totals actual files inside a specific path. Overlapping categories and cloud placeholders account for most of the gap.

Is it safe to delete C:\Windows.old on Windows 11?

Does scanning a drive interfere with Storage Sense?

Why does OneDrive show a huge folder that doesn't match my free disk space?

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Last reviewed by the jam-software.org editorial team on September 15, 2026. Spotted something out of date? Tell us.