If your storage drive keeps saying it's out of space and you're not sure what's taking up space, check your temporary files. These files can grow silently, sometimes taking up tens of gigabytes of storage space without you even realizing it.

What exactly are temporary files?

Windows creates temporary files (usually with a .tmp extension) every time you run software, install updates, or browse the web. These files are used to temporarily store data needed by the program to perform tasks, such as saving downloaded installation components, caching browser images, or recording document recovery information.

The problem is that many programs don't actively clean up these files after use. Although Windows automatically cleans up some temporary data on a regular basis, applications often leave behind crash logs, installation remnants, and cache content, which requires you to clean them up manually.

For older computers with traditional mechanical hard drives, it's not just a matter of storage space. When a directory accumulates tens of thousands of files, a mechanical hard drive becomes significantly slower at reading that directory—although this effect is almost imperceptible on modern SSDs due to their blazingly fast random access speeds, the HDD is put under additional strain.

Windows updates are often one of the "culprits." After completing a major update, the system will generate a folder similar to Windows.old or Windows-BT , occupying more than 20GB of space. These files save installation data from older versions of Windows to allow users to roll back the system. While this feature sounds useful, once the updates are confirmed to be working properly, these files take up valuable storage resources for a long time.

The easiest way to delete temporary files

Windows comes with a Disk Cleanup tool that helps you safely delete temporary files and other useless data without accidentally deleting important files. To launch the tool, click the Start menu, type Disk Cleanup , and open it from the search results.

Then select the primary drive and click OK . The system will scan the selected drive for redundant files and list everything that is safe to delete. Temporary files, Windows Update cleanup items, thumbnails, etc. are all selected by default. If not, please manually check the Temporary Files option under File Cleanup .

For a more thorough clean, click Clean System Files , select the drive again and confirm. More items that can be removed are displayed, such as previous Windows installation files and system error memory dump files. Unlike manual deletion, Disk Cleanup does not affect files currently being used by programs.

After selecting, click OK , then click Delete Files to confirm the operation.

You can also delete these files manually

If Disk Cleanup cannot clear all temporary files, you can also clean them manually. Press the Win R shortcut key, enter %temp% , and then press Enter to open the current user's temporary folder in the file explorer.

Press Ctrl A to select all files, then press Delete key to delete them. If some files are being used and cannot be deleted, the system will prompt an error. In this case, just click Skip to continue.

There is also a system-level temporary folder located in C:\Windows\Temp , which also accumulates a large amount of temporary data. Cleaning this directory requires administrator privileges. You can also use Ctrl A to select all during operation to delete files that can be deleted and skip files that cannot be deleted.

Although it is possible to force clear temporary files manually, this must be done with caution. Never delete files you don't understand. It is recommended to only clean known temporary paths, such as %temp% in the user directory and C:\Windows\Temp in the system directory.

Do not delete the Prefetch folder as it takes up almost no actual storage space. This folder contains data used to speed up program startup, and deletion may cause applications to start slower until the system regenerates these cache files.

Automatically clean temporary files with Storage Sense settings

In Windows 11, you can enable Storage Sense for automatic cleanup. This feature continuously monitors the storage device and automatically removes unnecessary files to free up space when conditions are met.

To turn on this feature, go to Settings > System > Storage and click Configure Storage Sense under Storage Management . Next check the Temporary File Cleanup option.

Then turn on the switch to automatically clean up user content . In addition, you can set how often Windows performs cleaning and choose whether to clean the contents of the Recycle Bin and Downloads folder. If you are unsure, it is recommended to keep the default settings or set to "Never".

You can also have Storage Sense automatically free up space in OneDrive for local files that are not frequently accessed, while retaining cloud access. In addition, it can automatically handle those huge Windows update residual files and automatically delete old system files after the 10-day "rollback" period provided by the system.

Setting up Storage Sense only takes a few minutes, but it can save you a lot of time in manual maintenance. This feature is particularly useful when you use an SSD with a smaller capacity. The tool runs silently in the background and automatically performs cleanup tasks only when set conditions are met.

Cleaning up your computer in just ten minutes at a time can prevent you from running out of storage space at critical moments. Whether you choose to delete them manually, use a disk cleanup tool, or enable automated Storage Sense, regularly cleaning out temporary files can make your computer run smoother and make more free space on your hard drive.

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