How do I change file extensions in Windows?

To change a file's extension, you must first enable file extension display in Windows. It is disabled by default. Once file extensions are displayed, you can use the file rename functionality to change a file's extension.

Display file extensions

The process of telling Windows Explorer to display file extensions is pretty much the same, regardless of what version of Windows you are using.

  1. Open My Computer or Windows Explorer
  2. If you want to turn the display of file extensions for all folders, it doesn't matter what's being displayed, but if you are just turning it on for the directory that your file is in, go to that directory. If the file is an email attachment that you saved from Webmail, it will be in your Download directory.
  3. What you do next is different depending on whether you are using Vista/Window 7 or an older version of Windows.
    • Older Windows: Click Tools on the main menu, then Folder Options...
    • Vista and Windows 7: Click Organize on the main menu, then Folder and search options.
  4. Click the View tab. Scroll down to Hide extensions for known file types. Click in the box to remove the check on this option.
  5. If you would like to have Windows always show file extensions, click the Apply to All Folders | Apply to Folders button. When it asks whether you want this to apply to all folders, click Yes.
    Windows XP 

    Windows Vista and 7

  6. Click OK.

Rename the file

  1. In Windows Explorer, go to the directory that the file is in. If the file is an email attachment that you saved from Webmail, it will be in your Download directory.
  2. Either right-click on the filename and select Rename from the right-click menu:
    Or click on the name of the file twice, pausing for a short while between the two clicks. 
  3. Change the file extension. In the images, the example is a file that was sent by email that Mimedefang has added an extra .txt extension to. Do not save these types of files and remove the.txt unless you are absolutely sure the file is not a virus; Mimedefang is usually right about such things. 
  4. After you have fixed the file's name, click outside the file name box to accept the new name.
  5. Because you have changed the file's extension, which might change how the file is used in Windows, a dialog box opens asking whether you are sure. If you are, click Yes, which finishes the process.

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Last updated: 

August 18, 2012

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