How to Change a File Extension on Windows 10

To change a file extension on Windows 10, first make file name extensions visible in File Explorer, then rename the file and replace only the characters after the final period. Windows will warn you before it applies the new extension. The important limitation is that renaming an extension does not convert the file to a different format; it only changes the file name and how Windows and apps may try to handle it.

Show file name extensions first

Windows 10 can hide extensions for recognized file types, so a file may appear as report even though its full name is report.txt. Make extensions visible before editing anything so you know exactly which part of the name you are changing.

1. Open File Explorer. You can press Windows + E to open it quickly.
2. Open the View tab on the ribbon.
3. In the Show/hide section, select File name extensions.

Microsoft documents this Windows 10 setting in its instructions for making file extensions visible in File Explorer. You can also use File Explorer's Folder Options and clear Hide extensions for known file types, as described in Microsoft's File Explorer help.

How to change a file extension on Windows 10

1. Open the folder that contains the file. If the file is important, consider making a copy first so you can easily restore the original name.
2. Select the file and press F2, or right-click it and choose Rename. File Explorer makes the name editable.

3. Replace the existing extension. For example, change report.txt to report.md. Keep the period between the base file name and the extension. Extensions are not always three letters: common examples include .docx, .xlsx, .jpeg, and .webp. If a file name contains several periods, the extension is normally the part after the final period.

4. Press Enter. Windows displays a warning that changing a file name extension might make the file unusable.
5. If you are certain the new extension is correct, click Yes. If you are unsure, click No and verify the file type before trying again.

The file's icon or default app association may change after the rename because Windows now sees a different extension. Microsoft notes that an extension identifies a file type and helps Windows determine which applications can open it; its file name extension reference also confirms that changing the extension does not convert the underlying file format.

Changing an extension is not the same as converting a file

This distinction prevents the most common mistake. Renaming photo.jpg to photo.png does not turn JPEG image data into PNG data. Likewise, renaming song.mp3 to song.wav does not re-encode the audio. An application may refuse to open the renamed file because the contents no longer match what the extension suggests.

If you truly need a different format, open the file in an application that supports the original format and use an option such as Save As, Export, or a trusted conversion tool. Use direct extension changes mainly when the file was given the wrong extension, an extension was omitted, or a workflow specifically requires a different recognized suffix without changing the underlying data.

What to do if the renamed file no longer opens

If a file stops opening after you change its extension, the quickest fix is usually to rename it again and restore the original extension. Renaming alone does not rewrite the file's contents, so reversing the name change normally restores the previous association.

• Do not guess extensions repeatedly. Use the source of the file, the application that created it, or a known specification to identify the correct format.
• Try Open with when the extension is correct. Right-click the file and choose Open with to select another compatible application instead of changing the extension just to force a different program.
• Keep extensions visible while troubleshooting. This helps you spot names such as document.pdf.txt, where the real extension is .txt, not .pdf.

Can changing a file extension damage the file?

Changing the extension by itself changes the name, not the file's stored data. However, the renamed file may become difficult to open or may be handled by the wrong application until you restore the correct extension. For that reason, use the rename method only when you know what the new extension should be. If your goal is to change the actual format, convert or export the file instead.