BMG File

What are BMG files and how to open them

Are you having problems opening a BMG file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your BMG files.

What is a BMG file?

A .BMG file is a Message String Storage file.

Message String Storage files are a binary text table format used by many Nintendo Wii and GameCube games to store all the text shown onscreen - menus, dialog, UI labels, track names, etc. These files are created by the game developers (using Nintendo's internal "JSystem" libraries), and at run-time the game console or emulator reads them to display localized text during gameplay.

Such files are organized into sections: a small file header defining overall size, number of sections, and character encoding; an INF1 section listing every message with offsets and attributes; a DAT1 section containing the actual text strings (in a "string pool" layout); optionally a MID1 section that maps each message to a numeric ID distinct from its position in the INF1 list. These messages may include escape tags (binary-embedded control codes) for formatting, color, font changes, or special inserts.

Typical tools made by the community (e.g. Wiimms SZS Tools) support converting these files to/from human editable text, enabling translation or modding. In Mario Kart Wii, for example, BMG files are inside language-specific SZS archives under /Scene/UI/messages; names like Common.bmg, Menu.bmg, Race.bmg are found there and hold UI text and track names.

Files begin with the ASCII signature "MESGbmg1" at offset 0 as an identifier.

How to open BMG files

Important: Different programs may use files with the BMG file extension for different purposes, so unless you are sure which format your BMG file is, you may need to try a few different programs.

While we have not verified the apps ourselves yet, our users have suggested two different BMG openers which you will find listed below.

Last updated: August 24, 2026

Various apps that use files with this extension

These apps are known to open certain types of BMG files. Remember, different programs may use BMG files for different purposes, so you may need to try out a few of them to be able to open your specific file.

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File.org helps thousands of users every day, and we would love to hear from you if you have additional information about BMG file formats, example files, or compatible programs. Please use the links below or email us at submit@file.org to discuss further.