What Is an MSI File?

Just double-click it to open it in Windows, or unzip it to see what's inside

What to Know

  • An MSI file is a Windows installer package file.
  • Windows Installer (it's built-in to Windows) opens MSI files.
  • Another way to see what's inside one is to extract its files with 7-Zip.

This article explains what an MSI file is and how to edit or open one. It also explains how to turn one into an ISO or EXE file.

What Is an MSI File?

A file with the .MSI file extension is a Windows installer package file. It's used by some versions of Windows when installing updates from Windows Update, as well as by other installer tools.

An MSI file holds all the information necessary for installing the software, including the files that should be installed and where on the computer those files should be installed to.

MSI files in a folder

How to Open MSI Files

Windows Installer is what the Windows operating system uses to open MSI files when they're double-clicked. It doesn't need to be installed to your computer or downloaded from anywhere because it's built-in to Windows. Just opening the MSI file should invoke Windows Installer, so you can install the files that are contained within it.

MSI files are packed in an archive-like format, so you can actually extract the contents with a file unzip utility like 7-Zip. If you have that or a similar program installed (most of them work similarly), you can right-click the MSI file and choose to open or extract the file to see all the files that are stored inside.

Using a file unzip tool is also useful if you want to browse the MSI files on a Mac. Since the MSI format is used by Windows, you can't just double-click it on a Mac and expect it to open.

Extracting the parts that make up an MSI file does not mean you can "manually" install the software—the MSI will do it for you automatically.

How to Convert MSI Files

To convert MSI to ISO is possible only after you extract the files to a folder. Use a file unzip tool like we described above so that the files can exist in a regular folder structure. Then, with a program like WinCDEmu installed, right-click the folder and select Build an ISO image.

Another option is to convert MSI to EXE, which you can do with Ultimate MSI to EXE Converter. The program is simple to use: select the MSI file and choose where to save the EXE file. There aren't any other options.

Introduced in Windows 8 and similar to MSI, APPX files are app packages that run in the Windows OS. See the tutorial at CodeProject if you need help converting MSI to APPX.

How to Edit MSI Files

Editing MSI files isn't as straightforward and easy as editing most other file formats like DOCX and XLSX files because it's not a text format. However, Microsoft offers the Orca program as part of the Windows Installer SDK that edits an MSI file.

To use Orca in a standalone format without the whole SDK, download this copy from Technipages. After you install Orca, right-click the MSI file and choose Edit with Orca.

Still Can't Open It?

MSI files should be fairly easy to open, especially in Windows. If it's not opening correctly or it isn't doing anything at all when you double-click it, first check your computer for viruses. MSI files can carry malware, and if your files is infected with something, it might appear to do nothing when it's opened.

Once you've ruled out malware, check that the file extension is correct in the sense that it says "MSI." If it's something else, then you're dealing with a different file format, in which case the information above is likely unhelpful.

For example, MSL files look related to MSI files, but only because the file extensions are similar (especially in lowercase: .msl vs .MSI). An MSL file is related to a script of some kind, meaning it can probably be viewed and edited in any text editor.

Another is MSIM, which is reserved for mSecure Password Manager backup files.

More on Windows Installer Files

"MSI" originally stood for the title of the program that works with this format, which was Microsoft Installer. However, the name has since changed to Windows Installer, so the file format is now the Windows Installer Package file format.

MSU files are similar but are Windows Vista Update Package files used by Windows Update on some versions of Windows, and installed by the Windows Update Standalone Installer (Wusa.exe).

MSIX files are based on the MSI format, but are ZIP-compressed packages used in Windows 10 and later. Microsoft's App Installer tool opens them, and any ZIP decompression tool, including 7-Zip, can extract its contents.

  • What is the difference between an EXE and an MSI file?

    While both are types of application installers, the primary difference between the two extensions is their purpose. While EXE is primarily used to indicate an executable file, MSI indicates a Windows installer file.

  • How do you install an MSI file from Command Prompt?

    Open an elevated Command Prompt, and then enter msiexec /a “pathtotheMSIfile” with the location of the MSI file, and press Enter.

  • How do you create an MSI file from an EXE?

    Run the .exe file, but don't proceed to installation. Go to the Windows temp folder (you can enter "%temp%" in the Run dialog), locate the MSI package for the EXE file, and copy the MSI package to your desired location.

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