Unfortunately, Windows 10 does not yet offer the possibility to detect duplicate files. Fortunately, there are many tools that can help you with this. If you really don't want to install extra software for this, you can still search and find duplicate files within Windows using a (somewhat cumbersome) trick.
Unfortunately, Windows 10 does not (yet) offer the possibility to detect duplicate files. With free software such as CCleaner or other programs for which you have to pay, you can easily find duplicates, but not everyone likes having to install a separate tool on his or her computer. With a (quite cumbersome) trick you can use Windows Explorer to find duplicate files yourself. Also read: 10 tips for Windows 10 Explorer.
Before you start cleaning, it's a good idea to create a backup in case you accidentally delete something you'd rather keep.
Sort and filter
When looking for duplicate files, it is important that you sort and filter them properly. The better you do this, the more likely you are to encounter duplicate files. And the more information you can find about files, the better you can compare them.
Tailor the view
In Windows Explorer, you can choose many different ways your files are displayed. Some views are better suited for file comparisons.
For example, the extra large icons make it easier to visually compare photos and videos. With the details view you can see a lot of extra information about all your files in a list, and it is possible to sort by these parameters.
by on Alt+P Pressing will open a panel with a preview of the selected file, allowing you to view a file directly from File Explorer without having to open it. This does not work for all file types, but it is very useful for images and documents.
by on Alt+V and then Alt+D pressing it immediately toggles a panel with details about the file in question.
Duplicate files have the same extension, so try to target only one file type at a time.
Note: For example, if you have an mp3 file and a wav file of the same music track, you might consider it "duplicate" or not because they differ in file type, sound quality, and application. So think in advance about how you want to treat such cases. I always choose to at least save the file in the highest quality.
For all file types, the size of the file is very important. Duplicate files have exactly the same file size, so if you sort by format you can quickly exclude all kinds of files as candidates.
Duplicate multimedia files are the easiest to identify as they contain a lot of metadata. For example, photos often contain information about the date and location they were taken, and sometimes also the type of camera. Music sometimes contains metadata about the artist and song title.
Of course, third-party tools are much faster and more accurate than this method with Windows Explorer, but if you prefer not to install new software, these tips will go a long way.
If you still want to try it with a tool, choose CCleaner, for example. Within the software, go to Tools - Duplicate File Finder and indicate which disk you want to search. Click on Ignoreon System Files, to prevent such files from being deleted. CCleaner is (as the name suggests) also a handy tool to clean your PC.