Is it safe to delete temp files on Windows?

Yes, it's safe to delete temp files on Windows. They are scratch files that apps were supposed to clean up and didn't. If an app is still using one, Windows simply won't let you delete it, so you can't break anything by clearing what's left.

Quick verdict:

• Contents of your Temp folder (%TEMP%, usually C:\Users\<your name>\AppData\Local\Temp): safe to delete. Skip files that are in use.
• Contents of C:\Windows\Temp: safe to clean, but do it with Settings or Disk Cleanup, not by hand.
• The Temp folders themselves: leave them in place. Delete what's inside, not the folder.
• Other "temp" things, like the Downloads folder that the Temporary files page also offers: check before you tick them.

What are temp files?

Windows has two main Temp folders.

Your personal Temp folder, %TEMP%. Each user account has one, normally at C:\Users\<your name>\AppData\Local\Temp. Apps you run use it for unpacked installers, document autosaves, previews, downloaded updates and similar short-lived files. Microsoft's GetTempPath2 documentation explains how Windows picks it: it looks at the TMP and TEMP environment variables first, which point here by default.

The system Temp folder, C:\Windows\Temp. Windows services, installers running with administrator rights and some drivers write here. On recent versions of Windows, processes running as SYSTEM may use C:\Windows\SystemTemp instead, a folder only the system can open.

Why does Temp grow? An app should delete its temporary files when it's done, but installers, updaters and apps that crash or get closed abruptly often leave theirs behind. Nothing cleans them up unless you, Storage Sense or Disk Cleanup do. That's how you end up with thousands of files and sometimes several gigabytes. Folders named SquirrelTemp, by the way, belong to the installer that Discord, Slack and other apps use; see SquirrelTemp, SquirrelSetup.log and Squirrel.exe.

How much space does it use?

The quick built-in check is Settings → System → Storage. Windows lists Temporary files with a size. Click it to see the breakdown.

For your own Temp folder only, open PowerShell and run:

"{0:N1} GB" -f ((Get-ChildItem $env:TEMP -Recurse -Force -ErrorAction SilentlyContinue | Measure-Object Length -Sum).Sum / 1GB)

To see what is taking the space, a disk space analyzer is easier. With SquirrelDisk, which is free:

1. On the home screen, click A folder and paste %TEMP% (or %LocalAppData%\Temp) into the folder dialog. From a terminal, squirreldisk %TEMP% does the same.
2. The chart builds while it scans, with the biggest items listed first. Click a slice to look inside.
3. If you want to remove something, drag it into the collector and choose Move to Trash (the Recycle Bin). SquirrelDisk asks for an extra confirmation because Temp lives inside AppData.

SquirrelDisk runs as your normal user and won't delete anything inside C:\Windows, so it can show you C:\Windows\Temp but you'll clean that one with the Windows tools below.

How to delete it safely

The built-in way (recommended)

1. Open Settings → System → Storage → Temporary files.
2. Wait for Windows to finish scanning. Tick Temporary files, and anything else you're happy to remove.
3. Read the list before you click. Downloads and Recycle Bin can appear here too, and they may contain files you want to keep.
4. Click Remove files.

This cleans both your Temp folder and C:\Windows\Temp, along with other Windows leftovers.

Disk Cleanup still works on Windows 11 if you prefer it. Search for "Disk Cleanup", pick drive C:, tick Temporary files, and click OK. Click Clean up system files first to include system items. Microsoft's cleanmgr reference notes it only deletes temporary files not modified within the last week, which is why it often frees less than you expect.

The manual way

1. Close the apps you have open, and finish any install or update in progress. A restart beforehand is even better.
2. Press Win + R, type %temp% and press Enter. File Explorer opens your Temp folder.
3. Press Ctrl + A to select everything, then Delete. Use Shift + Delete if you don't want it in the Recycle Bin.
4. When Windows says a file is in use, tick Do this for all current items and click Skip. Those files belong to running apps. Leave them.

That's it. Whatever is left is either in use now or will be cleaned next time.

What you should not delete

• The Temp folder itself. Apps expect it to exist. Empty it, don't remove it.
• Files during an install or update. Installers unpack into Temp and come back for those files a moment later. Deleting them mid-way can make the install fail.
• C:\Windows\Temp by hand while Windows Update is working. Use Settings or Disk Cleanup, which know what to leave alone.
• The TEMP and TMP environment variables. Don't change or remove them to "turn off" temp files. Apps will fail in odd ways.
• Unsaved work. Some apps keep autosaves or recovery files in Temp. If an app crashed and offered to recover a document, recover it before you clean up.

If something does go wrong, it's usually an install that failed: run the installer again and it will recreate what it needs.

How to stop it growing back

You can't stop apps from creating temp files, but you can have Windows clean them for you. Turn on Storage Sense in Settings → System → Storage. Microsoft's Storage Sense guide explains the options: it clears temporary files, can empty the Recycle Bin after a set number of days, and runs on a schedule you choose or when space is low. It only looks after drive C:.

If Temp keeps filling up fast, one app is usually responsible. Scan the folder, look at the file names or subfolder names of the biggest items, and you'll often recognise the app. Updating or reinstalling it tends to fix the leak.

Temp is rarely the biggest thing on a full drive. Once it's clean, have a look at the AppData folder and Windows.old, which are often much larger.