The file extension tells your computer what type of file it is and what software on your computer to use to open the file. The easiest way to change a file's extension is to save the file as a different file type than in a software program. Changing the file extension by changing the file name will not change the file type, but will cause your computer to misrecognize the file. On Windows and Mac OS X, file extensions are often hidden. This article describes how to save files as other file types in most software programs, and how to show file extensions in Windows and Mac OS X.
Step
Method 1 of 4: Changing File Extensions in Almost Every Software Program
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Step 1. Open a file with the default software program
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Step 2. Click the File menu, then click Save As
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Step 3. Choose a location to save the file
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Step 4. Name the file
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Step 5. In the Save As dialog box, look for the dropdown menu labeled Save As Type or Format
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Step 6. Select a new file type for the file from the dropdown menu
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Step 7. Click the Save As button
The original file will still open in the software program.
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Step 8. Find the new file where you saved it
Method 2 of 4: Show File Extensions in Windows
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Step 1. Open Control Panel
Click the Start menu, then click Control Panel. If you are using Windows 8, click here.
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Step 2. In Control Panel, click Appearance and Personalization
In Windows 8, on the ribbon, click Options
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Step 3. Click Folder Options
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Step 4. In the Folder Options dialog box, click the View tab
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Step 5. Make the file extension visible
In the Advanced settings list, scroll down until you see "Hide extensions for known file types". Click the box to uncheck it.
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Step 6. Click Apply, then click OK
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Step 7. Open the Windows Explorer file browser to see the file extensions
Method 3 of 4: Show File Extensions in Windows 8
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Step 1. Open Windows Explorer
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Step 2. Click the View tab
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Step 3. In the View/hide section, check the "File name extensions" box
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Step 4. If you open a new Windows Explorer window, the file extension will be visible
Method 4 of 4: Show File Extensions on Mac OS X
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Step 1. Select a Finder window or open a new Finder window
You can also click Desktop to switch to Finder.
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Step 2. Click the Finder menu, then click Preferences
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Step 3. In the Finder Preferences window, click Advanced
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Step 4. Click Show all filename extensions to put a check mark
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Step 5. Close the Finder Preferences window
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Step 6. Open a new Finder window
The files will show the extension.