To show file extensions in Windows 11, open File Explorer and select View > Show > File name extensions. After that, every file shows its full name, such as report.docx or setup.exe, instead of just report or setup.
The steps below cover that toggle, the older Folder Options route, and what to check before you rename an extension.
Why Windows hides the part you need
A Windows file name has two parts separated by a period: the name and an extension that defines the file type. Microsoft's file extensions page uses expenses.xlsx as its example, where expenses is the name and xlsx is the extension. The extension tells Windows which app can open the file and which icon to show.
The catch is that extensions for known file types are hidden by default in Windows 11, according to an Eleven Forum tutorial. That is why you see a Word icon and a name but no .docx.
Method 1: The View menu toggle
This is the route Microsoft gives on its File Explorer help page.
- Open File Explorer. Select it on the taskbar or Start menu, or press Windows logo key + E.
- Select View > Show > File name extensions.
The setting applies across File Explorer. Select the same item again to hide extensions.
Method 2: Folder Options
If you prefer the classic settings window, or the View menu doesn't behave as expected, use Folder Options. Microsoft's File Explorer page lists these steps:
- Open File Explorer from the taskbar.
- Select View > Options > Change folder and search options.
- Open the View tab.
- Under Advanced settings, untick Hide extensions for known file types.
- Select OK.
The Eleven Forum tutorial also describes a "Show file extensions" toggle in Settings, plus Registry methods. Microsoft's pages don't document those, so the two File Explorer routes above are the ones to rely on.
On a work or school PC, if neither setting sticks, ask your IT department.
How to read a name like invoice.pdf.exe
Once extensions are visible, read the file type from the last part of the name, after the final period. In invoice.pdf.exe, the .pdf is just part of the name. The file is an .exe, which Microsoft's extension table lists as an "Executable program file". That is a program, not a document.
With extensions hidden, the same file could appear simply as invoice.pdf, which is exactly why this setting is worth leaving on. As general advice: if an attachment or download you expected to be a document ends in an extension for a program or script, don't open it.
A few entries from Microsoft's table to recognise:
| Extension | Microsoft's description |
|---|---|
| exe | Executable program file |
| bat | PC batch file |
| jar | Java architecture file |
The table also lists msi, cab and sys.
Renaming an extension: what it does and doesn't do
You can change a file's extension by renaming it, but Microsoft is explicit that this won't convert the file to another format. It changes nothing except the file name. Renaming photo.png to photo.jpg doesn't make it a JPEG.
Renaming does make sense when the content already matches the new type, such as a script you wrote in Notepad and saved as .txt that should really be .bat or .html.
To rename one, as general advice:
- Turn on file name extensions using Method 1 or 2.
- Select the file and press F2, or right-click and choose Rename.
- Replace the text after the final period, for example change
cleanup.txttocleanup.bat. - Press Enter.
Fix: the extension won't change
The most common reason a rename "doesn't work" is doing it while extensions are hidden. The box you edit then shows only the name, so typing cleanup.bat gives you a file whose full name is cleanup.bat.txt. It's still a text file. Turn extensions on, look at the real full name, and remove the extra .txt.
Wrong app opens the file
If the extension is right but the wrong program opens it, don't rename anything. Microsoft notes that most extensions work with more than one installed program, and it points to its "Change default apps in Windows" help article for choosing which one opens a file type.
If you're tidying up other File Explorer habits, the Windows 11 Clipboard History guide covers another setting that's off by default.
