Learn How to Change File Types in Windows 10

Why File Types Matter in Windows 10 and When You Might Need to Change Them

Every file on your computer has a file type, identified by the extension that appears after the filename — like .docx for Word documents, .jpg for images, or .mp3 for audio files. Windows 10 uses these extensions to know which program should open each file. When you double-click a file, Windows reads the extension and launches the appropriate application automatically. Understanding file types is foundational to working effectively on your computer, especially when you encounter files that won't open the way you expect or when you need to save work in a different format.

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You might need to change file types for several practical reasons. Perhaps you've created a document in Word but need to share it as a PDF with someone who doesn't have Microsoft Office. Maybe you have a photo in PNG format but need it as a JPG to upload to a website that accepts only that format. You could be working with audio files and need to convert an MP3 to a WAV for audio editing software. Sometimes Windows associates the wrong program with a file type — for example, opening image files in Notepad instead of an image viewer — and changing the file type association solves the problem.

The process of changing file types in Windows 10 isn't complex, but it involves understanding the difference between two distinct operations: converting a file to a different format (saving it as a different type) and changing which program opens a particular file type by default. This guide walks through both scenarios so you'll recognize which approach matches your situation.

Practical takeaway: Before attempting any file type changes, identify whether you want to convert an existing file to a new format or simply change which program opens that file type. This distinction determines which method you'll use.

Converting Files to Different Formats Using Built-In Windows 10 Applications

The most common file type change is saving a file in a completely different format. For documents, this is straightforward. If you're working in Microsoft Word, you can save your document as a PDF, plain text file, or older Word format all from the File menu. Open your document, click "File," select "Save As," and in the dialog box that appears, look for the "Save as type" dropdown menu. This dropdown lists every format that Word can produce. Select your desired format, choose where to save the file, and click Save. Windows 10 creates a new file in that format while keeping your original intact.

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For images, Windows 10 includes the Photos app, which provides basic format conversion. Open an image in the Photos app, click the three-dot menu icon, and look for an option to save a copy or edit. While the Photos app's conversion capabilities are limited, you can also right-click any image file, select "Open with," and choose "Paint" — a built-in application that's been part of Windows for decades. Paint can open most common image formats and save them in different formats. Open your image in Paint, go to File > Save As, and you'll see format options including BMP, PNG, JPG, GIF, and TIFF.

For audio files, Windows 10's built-in media player (called Groove Music or Media Player depending on your version) doesn't offer format conversion directly within the app. However, you can right-click an audio file and select "Open with" to explore what applications are installed on your system. Many computers come with software that handles audio conversion, or you can use free applications designed specifically for this purpose.

A critical point to remember: format conversion and simply renaming a file are not the same thing. Changing just the extension from .jpg to .png by renaming the file won't actually convert it — it just changes the label, and the file will likely fail to open properly. Genuine format conversion requires software that understands both the source and destination formats and translates the file's contents accordingly.

Practical takeaway: Use the "Save As" feature within your application to convert files to different formats. The application itself handles the actual conversion, not just the filename extension. For formats not supported by your current program, try opening the file in a different built-in application like Paint before seeking external software.

Changing File Type Associations in Windows 10 Settings

File type associations determine which program opens when you double-click a specific file type. If all your PDFs have been opening in Notepad instead of a proper PDF reader, or your image files open in an unexpected program, you need to change the association rather than convert the file. Windows 10 gives you straightforward ways to modify these associations through Settings.

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The first method uses the context menu — the menu that appears when you right-click a file. Locate any file of the type you want to change associations for. Right-click it and select "Open with." You'll see a list of programs available on your system. Choose the program you want to use as the default, and look for a checkbox or option that says "Always use this app" or "Set as default." Checking this box tells Windows to open all files of that type with this program going forward. This is the quickest method for one-off changes.

For more comprehensive control, use Windows 10 Settings. Click the Start button and type "Settings" to open the Settings app. Navigate to "Apps," then select "Default apps" from the left sidebar. This page shows categories for Mail, Calendar, Music Player, Photo Viewer, Video Player, and Web Browser, along with a section for "Choose default apps by file type." Scroll down to the "Choose default apps by file type" section to see an alphabetical list of file types recognized by your system. Click any file type you want to change, and Windows shows you the currently associated program along with options to change it.

You can also use the "Set defaults by app" option in the Default apps section. This method lets you select an application and specify which file types it should handle by default. This is useful if you've just installed new software and want to assign multiple file types to it at once. For example, if you install a new image viewer, you can open Set defaults by app, select that application, and check which image formats (JPG, PNG, BMP, etc.) you want it to open.

If a file type isn't listed in these standard locations, right-clicking the file itself and choosing "Open with" remains your most direct option. From there, select the program you want, and mark it as the default for that file type.

Practical takeaway: When a file opens in the wrong program, use right-click "Open with" and select your preferred program, checking the "Always use this app" option. For systematic changes across multiple file types, visit Settings > Apps > Default apps to make bulk adjustments.

Understanding File Extension Visibility and How to Show Hidden Extensions

By default, Windows 10 hides file extensions from view. This design choice aims to reduce clutter for casual users, but it can make troubleshooting file type issues more difficult. When you see a file named "Resume" in your folder, you might not realize whether it's "Resume.docx," "Resume.pdf," or "Resume.txt" — each would open differently. To change file type associations effectively or to understand what you're working with, you often need to see these extensions.

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Revealing file extensions is simple. Open File Explorer (click the folder icon on your taskbar), and look at the top menu. Click the "View" tab. In the ribbon that appears, look for a checkbox labeled "File name extensions." Click it to enable the display of extensions. From this moment forward, all your files will show their complete names with extensions throughout File Explorer. You can toggle this setting on and off whenever you want by returning to the same View tab.

With extensions visible, you can now see exactly what you're working with. A folder might contain "document.docx," "document.pdf," and "document.txt" — three different files with the same name but different purposes. You can also manually rename a file's extension to change its type, though this is more of a workaround than a proper format conversion. For instance, if you needed to test whether renaming a file would change how Windows treats it, you could change "photo.jpg" to "photo.png" by right-clicking and selecting "Rename." However, remember that this renames the label without converting the actual file contents, so the file might not open correctly or might display incorrectly.

Seeing extensions also helps you identify suspicious files. Sometimes malware or unwanted files hide behind double extensions, like "Resume.pdf.exe" — which is actually an executable program despite appearing to be