What the Windows.old folder is, why it appears after an upgrade, how long Windows keeps it and how to remove it safely.
Windows.old is a folder that Windows Setup creates on the system drive when you upgrade or reinstall Windows over an existing installation. It holds the previous Windows installation so you can go back to it or recover files, and Windows deletes it automatically after a limited period, usually ten days.
The folder keeps the previous system files, installed programs and the user profiles of the old installation, for example C:\Windows.old\Users\<name>\Documents. It is often 10-30 GB because it is a full copy of the earlier Windows.
While the folder exists, Settings > System > Recovery offers a 'Go back' option for a limited time after a feature update.
Removing it is safe once the new Windows works, your devices have drivers and you have copied any personal files you still need from the old user folders. After removal you can no longer go back to the previous version.
Windows removes the folder by itself after the rollback period, so deleting it early is only about getting the space back sooner.
The files belong to system accounts and are protected, so Explorer usually refuses or deletes only part of them. The supported ways are Storage Sense ('Temporary files' > 'Previous Windows installation(s)') and Disk Cleanup with 'Clean up system files'.
C:\Windows.old\Users and copy any personal files you still need.Note: Rain Cleaner lists Windows.old with its size and what you lose before anything is removed.
Last updated: 2026-10-08
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