What Windows.old is and why it takes up space

Windows.old is a folder Windows creates when you upgrade from one version to another — say, from Windows 10 to Windows 11. It contains your old operating system, your previous settings, and your old files. Windows keeps it for 10 days by default so you can roll back to your previous version if something goes wrong with the upgrade.

The folder typically uses 15 to 30 gigabytes of disk space, sometimes more. If your upgrade went smoothly and you have not needed to go back, you can delete it safely. After 10 days, Windows will delete it automatically — but if you need the space now, you can remove it yourself.

Before you delete Windows.old, make sure you have what you need from your old system. Once it is gone, you cannot restore your previous Windows version using the built-in rollback option. If you think you might need to go back, wait the full 10 days.

Key Takeaways

  • Windows.old contains your previous operating system and settings after a major Windows upgrade, and Windows deletes it automatically after 10 days.
  • You can delete Windows.old manually through Settings, Disk Cleanup, or File Explorer, but only if you no longer need to roll back your upgrade.
  • Deleting Windows.old requires administrator access and will free up 15 to 30 gigabytes of disk space on most systems.
  • If you delete Windows.old by mistake, you cannot recover it — make sure your upgrade is stable before removing it.

Delete Windows.old through Settings

The simplest method is through the Settings app. Open Settings, go to System, then select Storage. Look for Temporary files and click on it. You will see a list of items taking up space, including Previous Windows installation(s). Check the box next to it and click Remove files.

Windows will ask for confirmation. Click Yes and wait for the deletion to finish. This can take several minutes depending on the size of Windows.old and how fast your disk is. Do not shut down your computer or unplug it during this process.

If you do not see Previous Windows installation(s) in the Temporary files list, Windows.old may already be deleted, or it may not be showing up in this view. Try the Disk Cleanup method instead.

Delete Windows.old using Disk Cleanup

Disk Cleanup is an older Windows tool that still works well for this task. Press the Windows key and type Disk Cleanup, then open the app. Select your main drive (usually C:) and click OK. Windows will scan your disk for files it can safely remove.

Look for Previous Windows installation(s) in the list. Check the box next to it. You can also check other items like Temporary files and Recycle Bin if you want to free up more space. Click Delete Files and confirm.

Disk Cleanup will delete the selected items. This method is slower than the Settings method but works on older Windows versions and sometimes catches Windows.old when Settings does not.

Delete Windows.old manually through File Explorer

You can also delete Windows.old directly using File Explorer, but this requires administrator access and extra steps because Windows protects the folder. Open File Explorer and navigate to your main drive (usually C:). You should see Windows.old listed as a folder.

Right-click on Windows.old and select Delete. If you get a permission error, you need to take ownership of the folder first. Right-click Windows.old, select Properties, go to the Security tab, and click Advanced. Click Change next to the owner name, type your username, click Check Names, then OK. Check the box for Replace owner on subcontainers and objects and click explore.

Go back and try to delete Windows.old again. This time it should work. Manual deletion takes longer than the other methods because Windows has to process permissions on thousands of files inside the folder.

What to do if deletion fails or gets stuck

If the deletion starts but seems to hang, close File Explorer and try again. Sometimes Windows needs a restart before it will fully release the folder. Restart your computer and attempt deletion again using the Settings method.

If you get repeated permission errors even after taking ownership, restart in Safe Mode and try deletion there. Press the Windows key and type msconfig, open it, go to the Boot tab, check Safe boot, and click OK. Restart your computer, log in, and try deleting Windows.old again. When you are done, go back to msconfig and uncheck Safe boot.

If deletion still fails, the folder may be in use by a running process. Close all open programs, including background apps, and try once more. If nothing works, you can safely leave Windows.old alone — it will delete itself after 10 days.

How much space you will actually free up

Windows.old typically uses between 15 and 30 gigabytes, depending on how much software you had installed and how many personal files were on your system. Some systems see 40 gigabytes or more freed up. You can check the exact size before deleting: right-click Windows.old in File Explorer, select Properties, and look at the size shown.

If your disk is nearly full and you need space urgently, deleting Windows.old is one of the fastest ways to free up a large amount. Combined with emptying the Recycle Bin and removing old downloads, it can often give you enough room to work comfortably again.

When not to delete Windows.old

Do not delete Windows.old if you are still within the 10-day window after your upgrade and you think you might need to roll back. Rolling back to your previous Windows version is the only way to undo a major upgrade without losing your files and settings — once Windows.old is gone, that option disappears.

If your system is unstable after the upgrade, if you are missing drivers or software, or if you are still testing whether everything works the way you need it to, wait. Give yourself time to make sure the upgrade is solid before you delete the safety net.

Frequently Asked Questions

Can I recover Windows.old after I delete it?

No. Once Windows.old is deleted, it is gone permanently. You cannot use file recovery software to get it back because the deletion is handled by Windows at a system level. If you need to undo your upgrade after deleting Windows.old, you will have to reinstall your previous Windows version from scratch using installation media.

Will deleting Windows.old slow down my computer?

No. Deleting Windows.old will not make your computer slower. It will make it faster in one way: you will have more free disk space, which can improve performance if your drive was nearly full. The deletion process itself takes time, but once it is done, there is no ongoing impact.

What if Windows.old is not showing up in File Explorer?

Windows.old may be hidden. In File Explorer, go to the View tab and check Hidden items. If it still does not appear, Windows.old may have already been deleted automatically, or your upgrade did not create one. This happens on fresh installs or when upgrading from very old Windows versions.

Do I need to restart my computer after deleting Windows.old?

You do not need to restart, but it does not hurt. Some users report that restarting after deletion helps Windows fully reclaim the disk space and update the storage display in Settings. If you do not restart, the freed space should show up within a few minutes.

Can I move Windows.old to an external drive instead of deleting it?

Moving Windows.old is not practical because the folder is very large and contains system files with special permissions. Deleting it is faster and simpler. If you want to keep a backup of your old system, back up your important files separately before upgrading, rather than relying on Windows.old.