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What is a BAK File?


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Question: What is a BAK File?

Did you find a BAK file on your computer and wonder what program should open it? Maybe someone emailed you a BAK file but you're not sure how to use it. Perhaps you tried to open the BAK file but Windows told you that it could not open it.

Before you can open a BAK file (assuming it's even a file format that's intended to be viewed or edited), you'll need to determine what kind of file the .BAK file extension refers to.

Answer: A file with the BAK file extension is a Backup file.

Other types of files may also use the BAK file extension. If you know of any additional file formats that use the .BAK extension, please let me know so I can update this information.

How To Open a BAK File

The easiest way to open a BAK file is to double-click on it and let your PC decide which default application should open the file. If no program opens the BAK file then you probably don't have an application installed that can view and/or edit BAK files.

Warning: Take great care when opening executable file formats received via email or downloaded from websites you're not familiar with. See my List of Executable File Extensions for a listing of file extensions to avoid and why.

BAK files are generic backup files meaning any number of programs could have been the one that created the file. The program could have been a dedicated backup program or it could have been a program that simply created a backup (BAK) file of another important file.

For example, all of Autodesk's programs, including AutoCAD, use BAK files regularly as backup files. Other programs might as well, like your financial planning software, your tax prep program, etc.

With BAK files, the context is especially important. Where did you find the BAK file? Was the BAK file named the same as another program? Answering these questions could help find the program that opens the BAK file.

If you know of any other information about BAK files that might be helpful, please send me a quick email and let me know so I can update this page.

Tip: Use Notepad or another text editor to open the BAK file. Many files are text-only files meaning no matter the file extension, a text editor may be able to properly display the file's contents. This may or may not be the case with BAK files but it's worth a try.

If you find that an application on your PC does try to open the BAK file but it's the wrong application or if you would rather have another installed program open BAK files, see my How To Change the Default Program for a Specific File Extension guide for making that change in Windows.

How To Convert a BAK File

There are two main ways to attempt to convert a BAK file to another file type:

The first option involving opening the BAK file in its native program is preferable because it's both easier and will probably result in a more accurate file conversion. Of course if you don't have a program that opens BAK files, a third-party file conversion tool (the second option) could be very useful.

Important: You cannot usually change a file extension (like the BAK file extension) to one that your computer recognizes and expect the newly renamed file to be usable. An actual file format conversion using one of the methods described above must take place in most cases.

Still Having Problems Opening or Using a BAK File?

See Get More Help for information about contacting me on social networks or via email, posting on tech support forums, and more. Let me know what kinds of problems you're having with opening or using the BAK file and I'll see what I can do to help.

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