What Windows.old is and why it exists
Windows.old is a folder Windows creates when you upgrade from one version to another — usually when you jump from Windows 10 to Windows 11, or from an older build to a newer one. It contains your entire previous Windows installation: your old system files, settings, and sometimes your user files if something went wrong during the upgrade.
Windows keeps this folder for about 10 days after an upgrade so you can roll back to your previous version if the new one doesn't work. After that window closes, the folder just sits there taking up space — often 15 to 25 gigabytes or more, depending on how much was installed before. Once you're confident the new Windows version is working, deleting it is safe and recovers that disk space.
Key Takeaways
- Windows.old is a backup of your previous Windows installation created during an upgrade, and it takes up significant disk space after the first 10 days.
- You can safely delete Windows.old once you've confirmed the new Windows version works properly on your system.
- The easiest method is Disk Cleanup, a built-in Windows tool that handles the deletion without requiring administrator commands.
- If Disk Cleanup doesn't show the option, you can delete the folder manually through File Explorer, but you may need to take ownership of it first.
- Deleting Windows.old removes your ability to roll back to the previous Windows version, so only delete it if you're certain you want to keep the current version.
Using Disk Cleanup to remove Windows.old
The safest and simplest way to delete Windows.old is through Disk Cleanup, a tool built into Windows. Open the Start menu, type "Disk Cleanup" and select it. The tool will scan your drive and show you what can be deleted. Look for an entry called "Previous Windows installation(s)" — that's Windows.old. Check the box next to it and click "Delete Files" at the bottom.
Windows will ask you to confirm. Click "Delete" again, and the folder will be removed. This usually takes a few minutes depending on the size. You don't need administrator commands or special permissions — Disk Cleanup handles the technical side for you.
If you don't see "Previous Windows installation(s)" in Disk Cleanup, it may mean Windows.old has already been automatically deleted, or the folder is in a location Disk Cleanup doesn't check. In that case, move to the manual deletion method below.
Manually deleting Windows.old through File Explorer
If Disk Cleanup doesn't show the option, you can delete Windows.old directly. Open File Explorer and navigate to your C: drive (or whichever drive Windows is installed on). Look for a folder named "Windows.old" — it will be at the root level of the drive, not inside the Windows folder.
Right-click on Windows.old and select "Delete". If Windows won't let you delete it and shows a permission error, the folder is protected. You'll need to take ownership of it first. Right-click the folder, select "Properties", go to the "Security" tab, click "Advanced", then "Change" next to the Owner field. Type your username, click "Check Names", then "OK". After that, you should be able to delete the folder.
This process can take several minutes because Windows.old is large. Don't restart your computer while the deletion is running.
When not to delete Windows.old
Only delete Windows.old if you're certain you want to keep your current Windows version. Once it's gone, you cannot roll back to the previous version through Windows settings. If the new Windows version is causing problems you can't fix — driver issues, software incompatibility, or system instability — you'll need Windows.old to go back.
If you're still within the first 10 days after upgrading and you're unsure about the new version, wait. Use it for a week or two, test your programs and hardware, and make sure everything works the way you need it to. Once you're confident, then delete Windows.old.
How much space Windows.old actually takes up
Windows.old typically uses 15 to 30 gigabytes of disk space, though it can be larger if you had many programs installed before the upgrade. You can see exactly how much space it's using by right-clicking the Windows.old folder, selecting "Properties", and looking at the "Size" field.
If your drive is nearly full and you need space urgently, deleting Windows.old is one of the fastest ways to free up room. However, if you're low on disk space for other reasons — like a drive that's straightforward too small for your needs — you may need to look at other solutions, such as moving files to external storage or upgrading to a larger drive.
What happens after you delete Windows.old
After deletion, the space is marked as available for new files, but the old data isn't when ready wiped from the drive. If you later need to recover files from Windows.old, data recovery software might still find them — though this is not may provide and becomes less likely over time as new files are written to the drive.
Your current Windows installation is not affected by deleting Windows.old. Your programs, files, and settings remain exactly as they are. The only change is that you lose the ability to roll back to the previous Windows version through the Settings app.
Frequently Asked Questions
Can I delete Windows.old if I'm still within the 10-day rollback window?
Yes, you can delete it at any time, but you should only do so if you're certain you don't want to go back to the previous Windows version. Once it's deleted, the rollback option in Settings will no longer work. If you're still testing the new version, it's safer to wait.
What if Windows.old is taking up space but I can't find it in File Explorer?
Windows.old is sometimes hidden by default. In File Explorer, click "View" at the top, then check the box for "Hidden items". This will show hidden files and folders. If you still don't see it, the folder may have already been deleted automatically by Windows.
Will deleting Windows.old speed up my computer?
No, deleting Windows.old won't make your computer faster. It only frees up disk space. However, if your drive was nearly full, having more free space can prevent slowdowns caused by the drive being too crowded, so there's an indirect benefit.
Can I move Windows.old to an external drive instead of deleting it?
Moving it is technically possible but not practical. Windows.old is a system folder with permission restrictions, and moving it doesn't give you a usable backup — you can't restore from it like you could from the Settings rollback option. If you want to keep a backup, use Windows Backup or create a system image instead.
What if I deleted Windows.old and now I want to go back to the previous Windows version?
If Windows.old is gone and the rollback option is no longer available in Settings, you'll need to reinstall the previous Windows version from scratch using installation media. This will erase your current installation. Data recovery software might recover some files from the deleted Windows.old folder, but this is not may provide.