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Running Out of Disk Space

Beginner Storage & Disk Applies to: Windows 10, Windows 11

→ This problem on Windows 7 instead

C: drive shows almost full and Windows warns you're low on space.

Before you start: save any open work and note down what you were doing when the problem started — that context helps if you need to search further or ask for help.
  1. Run Storage Sense: Settings > System > Storage > turn on Storage Sense to automatically clear temp files and old downloads.
  2. Run Disk Cleanup, select "Clean up system files," and check boxes for Windows Update Cleanup and Temporary files — this alone often frees several GB.
  3. Check the Storage breakdown (Settings > System > Storage) to see exactly what's taking up space by category before deleting anything.
  4. Clean up the WinSxS component store, which can grow to several GB over time from old update versions: run "DISM /Online /Cleanup-Image /StartComponentCleanup" from an administrator Command Prompt.
  5. Check your hibernation file size if you don't rely on Hibernate: an administrator Command Prompt with "powercfg /hibernate off" removes hiberfil.sys entirely, which can be several GB depending on your installed RAM.
  6. Uninstall unused apps: Settings > Apps > Installed apps on Windows 11, or Settings > Apps > Apps & features on Windows 10 — sorted by size.
  7. Move large files like videos and photos to an external drive or cloud storage if you're still tight after cleanup.
Still not fixed? Send us the details and we'll help you dig further, or browse related guides in Storage & Disk.

Frequently Asked Questions

Is it safe to turn off hibernation?
Yes — turning off hibernation just disables one specific sleep mode (Hibernate) and removes the file it was reserving space for. Regular Sleep mode is unaffected, and you can turn it back on later with "powercfg /hibernate on" if you change your mind.
Will cleaning up the WinSxS folder break anything?
No — DISM's StartComponentCleanup command is a genuine, official Microsoft tool built specifically for this. It only removes superseded versions Windows no longer needs, not anything currently in use.
How much space should Disk Cleanup actually free up?
It varies a lot depending on how long since you last cleaned up, but freeing several GB (sometimes 10+ on a PC that's never had this done) is common, especially from old Windows Update files.

Related guides

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"Disk Error" or "Windows Detected a Hard Disk Problem"

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Running Out of Disk Space on Windows 7

C: drive shows almost full — the Windows 7 way of finding and clearing space (no Storage Sense here).

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