C drive full on Windows 11: how to free up space safely

Why the C: drive fills up

On most Windows PCs, C: is the drive that holds Windows, your apps and, by default, your personal folders. Windows needs free space on it to install updates and keep temporary files, so a nearly full C: drive causes trouble quickly.

The space usually goes to a handful of things:

• Temporary files left behind by apps and by Windows itself.
• A previous version of Windows. After an upgrade, Windows keeps the old version in a Windows.old folder for a limited time so you can go back.
• Your own files: downloads, videos, photos, game captures, project folders and phone backups.
• Apps and games, some of which are very large.
• System files and reserved space, which Storage settings shows under System & reserved, plus hidden files such as the hibernation file and space set aside for restore points.
• The Recycle Bin: deleted files keep using space until it's emptied.

Windows can show you most of this in one place, and you can deal with most of it using built-in tools. You don't need to download anything.

Free up space on C: with what's built into Windows 11

These steps follow Microsoft's current Windows 11 instructions. Microsoft's articles say they apply to Windows 11 and Windows 10, and some labels can differ slightly between Windows 11 updates.

1. See what's using the drive

Open Start › Settings › System › Storage. Windows shows the space used on the C: drive and its largest categories. Select Show more categories to see the rest, including System & reserved. Select any category to see what's in it.

2. Remove temporary files

1. In Settings › System › Storage, select Temporary files.
2. Wait for Windows to list what it found, with sizes, and read the list.
3. If Downloads appears in the list, untick it unless you've already checked that folder.
4. Select Remove files.

If you upgraded Windows recently, the list may include your previous version of Windows. Microsoft notes that deleting it can't be undone, and that you won't be able to go back to your previous version of Windows afterwards. Only remove it once you're happy with the new version.

3. Use Cleanup recommendations

In Settings › System › Storage, select Cleanup recommendations. Windows groups its suggestions into Temporary files, Large or unused files, Files synced to the cloud and Unused apps. Review each group, tick only the items you're sure about, and select Clean up.

4. Turn on Storage Sense

In Settings › System › Storage, turn Storage Sense on, then select it to choose its settings:

• Run Storage Sense: how often it runs.
• Delete files in my recycle bin if they have been there for over: how long deleted files are kept.
• Delete files in my Downloads folder if they haven't been opened for more than: if you keep working files in Downloads, don't set a period here that could remove them.
• Content will become online-only if not opened for more than: applies to OneDrive and other cloud content you're signed in to.

Storage Sense works only on your system drive, which is usually C:.

5. Deal with your own large files

In File Explorer, open Downloads, Videos, Pictures and Documents, and sort each folder by size. Move files you want to keep to an external drive or another drive. Delete the rest, then empty the Recycle Bin.

To stop new files from filling C:, open Settings › System › Storage › Advanced storage settings › Where new content is saved. There you can choose another drive for new apps, documents, music, photos and videos.

6. Make OneDrive files online-only

If you use OneDrive with Files On-Demand, files can stay in the cloud and download only when you open them. In File Explorer, right-click a OneDrive file or folder you rarely use and select Free up space. You can still see the files in File Explorer, but they no longer take up space on the drive, and you'll need an internet connection to open them.

7. Uninstall apps you don't use

Open Start › Settings › Apps › Installed apps, find an app you no longer use, and select More › Uninstall. Microsoft notes that some apps can't be uninstalled from Settings and must be removed from Control Panel instead.

8. Optional: hibernation and restore points

• Hibernation file. Windows keeps a hidden file called hiberfil.sys so the PC can hibernate. Microsoft explains how to turn hibernation off in How to disable and re-enable hibernation. Microsoft warns that hybrid sleep stops working when hibernation is unavailable, and that you can lose data if the power fails while hybrid sleep is turned on. Only consider this if you never use Hibernate.
• Restore points. Search Start for Create a restore point, select your C: drive, select Configure…, and use the slider to set the maximum disk space used for restore points. Keep enough space for at least one recent restore point.

About Disk Cleanup

Microsoft's current Windows 11 instructions use Storage settings and Storage Sense, as above. Microsoft documents the older Disk Cleanup tool in its Windows 10 instructions.