Running out of disk space on Windows 10 slows everything down and blocks updates. This guide covers 10 methods from Disk Cleanup to removing hidden WinSxS bloat — without risking your files.
In this guide
Search for Disk Cleanup in the Start menu, select your C: drive. Click "Clean up system files" at the bottom left — this elevates to admin mode and reveals extra categories including Windows Update Cleanup (often 5-10GB), Previous Windows installations, and Temporary Internet Files. Select everything and click OK.
After a major Windows upgrade, the old installation is kept in C:\Windows.old for 30 days as a rollback option. It can be 15-25GB. To remove it safely, use Disk Cleanup → System Files → Previous Windows installations. Do not delete it manually as some system files in that folder are locked.
WinSxS stores component backups and cannot be deleted manually, but you can reduce it. Open Command Prompt as Administrator and run: Dism.exe /online /Cleanup-Image /StartComponentCleanup /ResetBase. This safely removes superseded update components. On a typical system this recovers 3-8GB. Never delete files from WinSxS directly.
The hiberfil.sys file reserves RAM size on your drive for hibernation — on a 16GB RAM machine that is 12-16GB. If you do not use hibernation, open Command Prompt as Administrator and run: powercfg -h off. This immediately deletes hiberfil.sys and reclaims the space. Sleep mode still works; only full hibernation is disabled.
Download WizTree (free, faster than WinDirStat). Run it on C: to see a visual map of what is using space. Common large hidden consumers: game saves in AppData, old video renders in Downloads, crash dumps in C:\Windows\Minidump, and Docker image layers in C:\ProgramData\Docker.
If you have a secondary drive, right-click your Downloads, Documents, or Pictures folder → Properties → Location tab → Move. Point it to D:\Downloads (or similar). All future saves go to the secondary drive. Existing files move automatically. This is the most sustainable long-term solution if your C: drive is small.
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