How to clean out junk files in Windows 10

Free up gigabytes of space on your desktop, laptop or tablet -- no special tools required.

Tom McNamara Senior Editor / Download.com
6 min read

Just like your fridge, a computer's storage space needs to be cleaned out every once in a while to keep things running smoothly. "Temporary" files can get left behind permanently, and big updates to Windows may create many gigabytes of backup files that you never end up using. 

Many junk file cleaning apps go too far, however, such as deleting your web browser cache, which will refill itself anyway over time and whose files help you load websites faster. Let's show you how to tidy things up yourself, using Windows' own built-in tools.

The Disk Cleanup tool

Every storage device in your computer has access to the Disk Cleanup tool. Find it by clicking the Start button, typing "disk cleanup" (whenever I say to type something, I mean without the quotes), and clicking the Disk Cleanup shortcut in your search results. Click and drag this shortcut to your desktop or taskbar for easier access next time. You can also find the tool by right-clicking a storage device in File Explorer, selecting Properties, and clicking the Disk Cleanup button to the right of the pie chart.

Sometimes the shortcut doesn't show up in your search results. If this is the case, instead of typing "disk cleanup," type "free up disk space." A phrase may work when the name of the program doesn't.

If you have a lot of stuff to clean up, it may take the tool several minutes to analyze your situation and get your cruft organized for deletion. Once that's done, you'll be presented with a new window containing a list of things that are safe to delete. Some boxes are even prechecked, such as the one next to Temporary Internet Files.

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Browser and thumbnail caches

Browser and thumbnail caches can consume several gigabytes. When you load a webpage, it gets stored here for quicker access later, so cleaning out the cache can make future browsing slower.

Chrome and Firefox caches get cleaned from within those apps through a menu accessed by pressing Ctrl+Shift+Delete when the browser is open. It's preferable to do it within the browser, because you get more detailed control over what you want to keep and get rid of.

While wiping your browser cache only temporarily frees up space, it doesn't hurt to periodically wipe it clean and start fresh, if you have security or privacy concerns.

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Dealing with thumbnails

The Disk Cleanup tool has one list item specifically for thumbnails. Thumbnails include things like app icons and picture previews. But if you clear out this cache, Windows will have to regenerate those images the next time you view a folder with a lot of media or icons in it. Each thumbnail will also take time to recreate, so a large folder may take several minutes to rebuild its cache. If you're looking for a specific picture or video, you may have to wait until the thumbnail has been created, unless you know its file name. 

We recommend leaving the Thumbnails item in Disk Cleanup unchecked, unless the cache size is creating problems with your available free space.

System files

The biggest hoarders of your disk space are probably system files, so click the Clean up system files button to access them. This will perform another analysis, which can take a few minutes, especially if it detects those Windows Update backup files that we mentioned earlier. Then it will load a window that looks exactly like the analysis results window you saw in Disk Cleanup. 

This time, however, there are additional items in the list. If you're using Windows 7 , you may find several gigabytes of Service Pack Backup Files listed. In theory, this archive can be used to undo a service pack. In practice, it takes up a load of space, and it would be faster and more reliable to just restore from a previous backup image than to undo a service pack.

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System Restore

Windows uses System Restore to preserve system files in case they're accidentally deleted or corrupted. A system restore is like a bookmark or snapshot that the operating system can go back to. It doesn't back up the entire contents of your storage device, so it may not help you if you can't boot Windows at all. And these periodic bookmarks can end up hogging a lot of space. In fact, in Windows 8 and 10, System Restore is disabled by default, so you shouldn't need to mess with its settings unless you've enabled the feature yourself.

Unfortunately, Windows doesn't let you choose which restore points you want to keep, nor does it easily tell you how much disk space your restore points are taking up. The Disk Cleanup tool lets you delete all but the most recent one, and that's about it. To do so, go to the Disk Cleanup tool. Click Clean up system files, then the More Options tab, then go down to the System Restore and Shadow Copies section, then click the Clean Up button, and finally the Delete button to confirm.

Do you want to delete all your restore points? For that, you need a different tool. Click the Start menu button, right-click Computer, select Properties, click the System Protection link on the left-hand side, and click the Configure button to access your System Restore settings. If you don't have a Computer shortcut on your Start menu or your desktop, click the Start button, type "computer" to get it to come up in your search results, right-click it, select Properties, and you will be at the window where you click System Protection. Then click Configure.

You can disable System Restore altogether, tell Windows what percentage of disk space you want to dedicate to System Restore, and click the Delete button to delete all restore points. This window also shows you how much space your System Restore points are taking up. By default, Windows 7 sets aside about 5 percent of your storage device for restore points. So, in theory, it won't get crowded. But if you have a roomy storage device, that 5 percent can add up to a lot of gigabytes that may be better used elsewhere. And overall, creating system backup images and storing them on an external drive (or even in the cloud) will give you better control and more consistent results.

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The hibernation cache

When you turn off your Windows device, it can put your open apps and open files in a large file called the hibernation cache, to help you pick up where you left off when you turn your PC on later. Alternatively, sleep mode keeps this data in your system RAM and puts the device in a low-power mode. Hibernation mode doesn't draw battery power, so it's better for laptops and tablets . But it takes longer to boot up than restoring from sleep mode, which is more or less instant, so you sacrifice some convenience.

If your Windows device is usually plugged into a power outlet, hibernation mode probably won't be as useful as sleep mode, so you should be able to disable the hibernation cache without side effects. The storage space that you save is roughly equal to how much system RAM your device has.

To disable hibernation, click the Start button, type "cmd", right-click cmd.exe, select Run as Administrator, and click Yes to confirm. This is the Windows command prompt. Paste "powercfg.exe /hibernate off" into the command prompt. Ctrl-V doesn't work here in Windows 7, though. Instead, you have to right-click in the window and select Paste. Then hit Enter. If you want to re-enable hibernation mode later, paste "powercfg.exe /hibernate on". The change will take effect immediately.

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Managing the Recycle Bin

When you delete a file, Windows doesn't erase it by default. The file just goes to the Recycle Bin, where it will stay until you tell Windows to empty the bin. So the bin needs to be checked periodically to make sure your disk space isn't being used up by big files you no longer need.

You can also adjust how much storage the Recycle Bin uses. To do so, open the File Explorer (press Windows+E), find the bin in the left-hand pane, right-click it, and select Properties. The bin might not be displayed by default, in which case you need to right-click in the left-hand pane and select Show All Folders. (The Bin is technically a folder.)

In the Recycle Bin properties window, you can tell Windows the maximum amount of space you want to use for the bin. The default is 5 percent of your C: drive's storage capacity, and you can increase that to 10 percent. You can also tell Windows to skip the bin altogether, as well as disable the confirmation prompt that pops up when you attempt to delete a file. When you're done making your changes, click the OK button to save them.

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