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To free space on a full C drive, start with Settings > System > Storage. Windows shows where the space is going and offers cleanup recommendations you can review before anything is removed. Then turn on Storage Sense for ongoing cleanup, and move personal files you want to keep to another drive. Deleting files at random is slower and riskier than working from Windows’ own breakdown.
Quick workflow for a full C drive
- Open File Explorer, select This PC, and note the free space shown for C:.
- Open Settings > System > Storage and review the category breakdown.
- Select Cleanup recommendations, read each suggestion, and clean up only the items you are comfortable removing.
- Turn on Storage Sense from the Storage page. Before relying on it, check its options for the Recycle Bin, Downloads, and cloud files.
- Move large personal files you want to keep to another internal or external drive, or change where new content is saved.
- If a Windows update is blocked by lack of space, follow the update-specific route described below.
Return to This PC afterward and compare the free space on C: with the number you noted in step 1.
Find out where the space is going
The Storage page groups usage into categories such as Installed apps, Temporary files, System & reserved, and other usage. Treat this breakdown as a diagnostic view. A large category is not an instruction to delete it, especially when it contains files that Windows manages itself.
System and reserved storage
Windows sets aside reserved storage for temporary files, caches, and other system functions. When the device runs low on space, Windows can clear reserved storage for other processes, such as an update. Do not manually remove system-managed files based only on their size.
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Clean up with Cleanup recommendations
Cleanup recommendations show an estimated amount of recoverable space and suggest items to review. Each suggestion is a choice you make, not an automatic deletion. The categories you are most likely to see are below.
| Category | What it contains | What to check before removing it |
|---|---|---|
| Temporary files | Temporary and cached data that Windows creates | Select only the entries you want to clear and confirm the selection before continuing. |
| Previous Windows installation(s) | Files from an earlier Windows version, kept so you can roll back | Removing them ends the option to return to that earlier installation. Remove them only if you no longer need a rollback. |
| Large or unused files | Personal files flagged by size or by how long they have gone unopened | These are your files. Open each one you are unsure about before deleting it. |
| Rarely used apps | Installed apps that have not been opened recently | Confirm you do not need the app before uninstalling it. |
The space estimate Windows displays is specific to your PC at that moment. Check free space again after cleanup rather than relying on the estimate.
Turn on Storage Sense
Storage Sense can run automatically when the device is low on disk space, if it is enabled with default settings. Under those defaults it removes unnecessary temporary files and Recycle Bin content. Microsoft Support states that Storage Sense works on the system drive only, which contains the Windows operating system and is usually referred to as C:.
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Downloads and cloud content are not touched unless you configure them. Review those options on the Storage page before you rely on Storage Sense to keep C: clear.
Keep important files without filling C:
Photos, videos, music, and other files you want to keep but rarely use can be moved to another drive, including an external drive. The trade-off is access: moved files are only available while that drive is connected. Changing the default save location for new content also prevents the same drive from filling again.
OneDrive Files On-Demand
Files On-Demand stores a placeholder on your PC instead of the full file. Online-only files remain visible in File Explorer, but they need an internet connection to download and open. Storage Sense can make eligible inactive OneDrive files online-only. Files marked Always keep on this device are exempt from that management.
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On Windows 11 22H2 and later, Microsoft’s Storage Sense documentation says the default for OneDrive cloud files is online-only after more than 30 days unopened. This is a version-specific default, so check your own settings rather than assuming it applies to every PC.
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Choosing between the options
| Option | Frees space on C: | Access afterward |
|---|---|---|
| Delete after review | Yes | The file is no longer on the PC |
| Move to another drive | Yes | Only while that drive is connected |
| OneDrive online-only | Yes, for the local copy | Needs an internet connection to open |
| Always keep on this device | No | Available offline, and exempt from Storage Sense |
If a Windows update needs more space
Microsoft recommends running Storage Sense and reviewing Cleanup recommendations first when an update reports a space shortage. If Windows offers the Fix issues option for the update, Microsoft’s documented procedure can use an external storage device. Before you start:
- Have an external device with at least 10 GB of free space. This figure applies to that update procedure only, not to external storage in general.
- Have an internet connection.
- Back up important files before connecting the external device.
The PC may still need more free space on the internal drive, so an external device does not replace internal room.
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When cleanup keeps refilling
If cleanup does not hold, the cause may be a specific source that keeps writing files back. Microsoft documents one such case, in which the Temp folder fills quickly with Microsoft Store .appx files after cleanup. Use these steps only when that pattern matches your PC:
- Reset the Microsoft Store app from its settings page.
- Press Windows key + R, type wsreset.exe, and press Enter to clear the Store cache.
- Run Windows Update troubleshooting.
- Restart the PC, then check free space on C:.
This is a targeted branch for recurring low-space errors. It is not a routine first step for every full drive.
Malware as a possible cause
Microsoft’s general low-space troubleshooting includes a Store cache reset and advises scanning with Windows Security if malware is suspected. Malware is not established as a common reason for a full C drive, so run a scan only if you have other signs of infection, such as unexpected programs or pop-ups.
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- This USB drive provides plug and play simplicity with the included 18 inch USB 3.0 cable
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Windows 10 readers
Windows 10 support ended on October 14, 2025. The cleanup steps in this guide do not change because of that date, but the menu labels and options can vary by version and build, so follow what appears on your screen.
What the official guidance does not settle
Microsoft’s documentation does not give a typical amount of space that cleanup recovers, a general free-space figure Windows needs, or a recommended storage size for a PC. The only numeric requirement in the update guidance is the 10 GB external-device figure described above. Use the estimates in Cleanup recommendations and the category sizes on the Storage page as the measure for your own PC.
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