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How to free up space on your C: drive (Windows 11 and 10)

Updated

When the drive that holds Windows gets close to full, everything slows down: updates fail, apps stutter and the PC may refuse to install the next feature update. The good news is that most full drives can be fixed for free in half an hour, without deleting anything you care about.

How much free space do you need?

A practical rule we use: keep at least 15% of the drive, or 30 GB — whichever is larger — free on C:. Windows uses free space for updates, its page file, hibernation and temporary files, and SSDs need some empty room to keep their speed. On a 256 GB drive that's about 38 GB; on a 1 TB drive about 150 GB.

To see where you stand, open File Explorer, click This PC and look at the bar under Local Disk (C:). A red bar means it's critically low.

Step 1: Let Windows clean up after itself

  1. Open Settings (press Windows + I).
  2. Windows 11: go to System › Storage. Windows 10: System › Storage as well.
  3. Click Temporary files (Windows 11: under “Cleanup recommendations” you'll also find a quick list).
  4. Tick Windows Update Cleanup, Delivery Optimization Files, Temporary files, Thumbnails and Recycle Bin if you're sure it holds nothing you need.
  5. Leave “Downloads” unticked unless you've checked that folder first — this option deletes everything in it.
  6. Click Remove files.

After a big Windows update, “Windows Update Cleanup” or “Previous Windows installation(s)” can be many gigabytes. Removing previous installations means you can't roll back that update, so do it once you're happy the update works.

Step 2: Turn on Storage Sense

In the same Storage page, switch on Storage Sense. It quietly deletes temporary files and can empty the Recycle Bin after a set number of days. Click it to choose the schedule. It won't touch your documents or photos.

Step 3: Find what's actually big

In Settings › System › Storage, Windows shows categories: Apps & features, Temporary files, Other, Documents, Pictures, Videos and so on. Click Show more categories to see everything. The biggest category is usually where to start.

Step 4: Move personal folders to another drive

If your PC has a second drive (D: or similar), you can move whole folders so new files go there automatically:

  1. Open File Explorer, right-click Videos (or Pictures, Documents, Downloads) and choose Properties.
  2. Open the Location tab and click Move….
  3. Create or pick a folder on the other drive, such as D:\Videos, then click Apply and say Yes to moving existing files.

Don't move these folders to an external USB drive that you unplug — Windows expects them to always be there.

You can also change where new content goes: Settings › System › Storage › Advanced storage settings › Where new content is saved (Windows 10: Change where new content is saved).

Step 5: OneDrive files on demand

If you use OneDrive, right-click big folders inside OneDrive and choose Free up space. The files stay listed and download again when you open them — but only do this if you have a reliable internet connection.

Optional: hibernation

The hidden file hiberfil.sys can take several gigabytes. On a desktop that you never hibernate, you can turn it off: open Terminal (Admin) or Command Prompt as administrator and run powercfg /hibernate off. This also disables Fast Startup. On a laptop we suggest leaving it on.

What not to do

When cleaning isn't enough

If you've done all this and C: is still nearly full, the drive is simply too small for how you use the PC. The usual fix is a bigger SSD — see how to choose an NVMe SSD and how to move Windows to a new SSD. Adding a second drive for games and media is often even easier.

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