Software & Apps › File Types What Is an EX_ File and How Do You Open One? Decompressing EX_ files into EXE executable files Share Pin Email Print File Types Design Cryptocurrency MS Office Windows Linux Google Drive Apps File Types Backup & Utilities View More By Tim Fisher General Manager, VP, Lifewire.com Tim Fisher has 30+ years' professional technology support experience. He writes troubleshooting content and is the General Manager of Lifewire. our editorial process Facebook Twitter LinkedIn Tim Fisher Updated February 11, 2020 A file with the EX_ file extension is a compressed EXE file. This format stores an EXE file with a smaller size to save storage space. You might also find the EX_ format within compressed installation files that you download from the internet. Windows can't execute an EX_ file. For example, you can't accidentally open an EX_ file to run the program until the file extension is renamed to EXE. Take great care when opening all kinds of executable files with extensions like EXE, COM, BAT, and others you're not familiar with. These files can be extremely dangerous to your system, personal data, and overall security. Never open an executable file sent to you over email or that you don't know explicitly what it does. How to Open an EX_ File You'll first need to convert the EX_ file to an EXE file before you can run the file. Use the expand command from the Command Prompt in Windows. Open Windows Explorer and access the EX_ file location. In an area of the folder where there are no files, press Shift+Right Click. In the context menu that opens, select Open command window here; if you're using Windows 10, select Open PowerShell window here. At the command prompt in the new window, enter the following command, substituting file.ex_ with the name of the EX_ file you want to expand. The second file.exe is the name you want to give the expanded file: expand file.ex_ file.exe The new EXE file will be created as named. No changes will be made to the original EX_ file. Another option for entering the expand command: Open Command Prompt and type the expand command followed by a space. Then simply drag the EX_ file to the command prompt and drop it. This trick automatically fills the location of the EX_ file and name. Type the name of the EXE file you want the expanded file to be called. When EX_ Isn't a Compressed EXE File If the method above doesn't work, check to see that the EX_ file is actually a compressed EXE file. Using Notepad++, open the EX_ file. Notepad++ may reveal some descriptive information that can help you determine what program should be used to open that file. If you find that a specific application should be used to open the EX_ file, change the default program for that file extension. You may also discover that the EX_ file is not actually compressed, but is an EXE file whose extension was simply renamed to EX_. Return it to an executable file format. Right-click on the file and select Rename. Change the extension from .ex_ back to .exe and press Enter.