That red bar under Local Disk (C:) in File Explorer is hard to miss. Once your C drive is full, Windows slows down, updates fail to install, and apps start throwing odd errors. It can creep up on you, especially on laptops with a 256 GB SSD.
The good news is that you can usually reclaim several gigabytes in 15 minutes without deleting anything you care about. Here are ten safe ways to fix a C drive full warning on Windows 11.
First, see what is taking up space
Open Settings > System > Storage. Windows breaks down your drive into categories like Apps, Temporary files, Documents and Pictures. Click Show more categories for the full list. This tells you where to focus, rather than guessing.
1. Delete temporary files
- In Settings > System > Storage, click Temporary files.
- Wait for the scan to finish, then tick the boxes you want to remove.
- Click Remove files.
Be careful with the Downloads box. It deletes everything in your Downloads folder, so leave it unticked unless you have checked that folder first. Windows Update Cleanup, Delivery Optimization Files and Temporary files are all safe to remove.
2. Use Cleanup recommendations
In the same Storage page, click Cleanup recommendations. Windows lists large or unused files, files already synced to OneDrive, and apps you have not opened in a while. Review each list and remove what you do not need.
3. Turn on Storage Sense
Storage Sense cleans up automatically so the problem does not come back.
- In Settings > System > Storage, switch on Storage Sense.
- Click it to choose how often it runs and whether it empties the Recycle Bin and Downloads after a set number of days.
4. Run Disk Cleanup for system files
The classic Disk Cleanup tool still exists, and it can remove a few extra things.
- Press Windows + R, type cleanmgr, and press Enter.
- Choose drive C: and click OK.
- Click Clean up system files, select C: again, and wait.
- Tick the items you want removed and click OK.
If you upgraded Windows recently, you may see Previous Windows installation(s), which can be 10 GB or more. Deleting it means you can no longer roll back to the previous version, so only remove it once you are happy with the update.
5. Uninstall apps and games you do not use
Games are often the biggest space hogs, easily 50 to 100 GB each. Go to Settings > Apps > Installed apps, sort by Size, and uninstall anything you no longer use. Preinstalled trial software from the laptop maker is another easy win.
6. Empty the Recycle Bin
Deleted files are not really gone until you empty the Recycle Bin. Right-click it on the desktop and choose Empty Recycle Bin. It sounds obvious, but it can hold gigabytes.
7. Move personal files to another drive
If your PC has a second drive (often D:), move big folders like Videos, Pictures and Downloads there. The neat way is to right-click the folder in File Explorer (for example, Videos), choose Properties > Location, click Move, and pick a folder on the other drive. Windows then saves new files there automatically.
An external drive or USB stick also works well for archives you rarely open.
8. Use OneDrive Files On-Demand
If you use OneDrive, you can keep files in the cloud without storing them on your PC. Right-click a large folder inside OneDrive and choose Free up space. The files still appear in File Explorer and download automatically when you open them. Our guide to what cloud storage is explains how this works.
9. Turn off hibernation (if you do not use it)
Hibernation saves a file called hiberfil.sys that is often several gigabytes, roughly a portion of your RAM size. If you never use hibernate, open Terminal (Admin) and run:
powercfg /h offTo turn it back on later, run the same command with on instead of off. Note that this also disables Fast Startup.
10. Find big forgotten files
Open File Explorer, click the C: drive, and type size:gigantic in the search box to find files over 4 GB (or size:huge for 1 to 4 GB). Old video exports, disk images and installers often turn up here.
What not to delete
Never manually delete files from C:Windows, WinSxS, Program Files, or System32, and avoid “registry cleaner” apps. These can break Windows. Stick to the built-in tools above.
If your PC still feels slow after freeing space, check our guides on how to speed up a slow Windows 11 PC and fix 100% disk usage. Microsoft explains storage tools further on its Windows support site.
Quick recap
When your C drive is full, start in Settings > System > Storage: remove temporary files, follow Cleanup recommendations and turn on Storage Sense. Run Disk Cleanup for system files, uninstall unused apps, move personal folders elsewhere and use OneDrive’s Free up space. You will often get back 20 GB or more without losing anything that matters.
