This article describes what DMG files are, how to open them on different operating systems, and how to convert them to another archive format, such as ISO or IMG.

A file with the DMG file extension is an Apple Disk Image file, or sometimes also called a Mac OS X Disk Image file, which is essentially a digital reconstruction of a physical disk.

For this reason, a DMG is often the file format used to store compressed software installers instead of using a physical disk. You'll probably only see them when downloading macOS software from the Internet.

This macOS disk image format supports compression, file size, and encryption, so some DMG files may be password protected.