How to free up space on Windows 10 and 11 without breaking anything

01Measure before deleting

Open Settings › System › Storage. Windows shows what takes up the disk there: apps, temporary files, documents, other. On Windows 11, Cleanup recommendations also lists large files, rarely used apps and files already synced with OneDrive.

Write down the free space before you start, so you see what each step actually freed.

02Temporary files

In Storage › Temporary files, Windows lists what it can delete: temporary files, Windows Update Cleanup, Delivery Optimization files, thumbnails, Recycle Bin… All of it can be deleted safely.

One exception: the Downloads box deletes your entire Downloads folder. Only tick it after checking that folder.

The older Disk Cleanup tool (type “Disk Cleanup” in the Start menu, then Clean up system files) does the same thing and is still useful on Windows 10.

03Turn on Storage Sense

Storage › Storage Sense automatically cleans temporary files and can empty the Recycle Bin after 30 days. Set Downloads to “Never” if you keep useful files there: otherwise they will be deleted after the chosen delay.

04Windows.old after an upgrade

After an upgrade (Windows 10 to 11, or a yearly feature update), the previous installation stays in C:\Windows.old, often more than 10 GB. It lets you roll back for 10 days, then Windows deletes it itself.

To delete it sooner: Temporary files › Previous Windows installation(s). You will no longer be able to go back to the previous version: only do it if everything works.

05Hibernation and restore points

The hiberfil.sys file takes about 40% of your RAM (6 GB for 16 GB of RAM). If you never use hibernation, turn it off in a Terminal opened as administrator:

This also turns off Fast Startup. powercfg /hibernate on brings both back.

Restore points can take up to 10% of the disk. In the Start menu, type “Create a restore point”, choose the C: drive, then Configure: lower the maximum usage, or delete existing points. Keep at least one recent point.

06OneDrive, apps and large files

With OneDrive, right-click a synced folder › Free up space: files stay in the cloud and download when opened.

In Settings › Apps › Installed apps, sort by size and uninstall what you no longer use. Games are often the heaviest.

Finally, in File Explorer, open Downloads and Videos in Details view and sort by Size: forgotten installers and videos come first.