What is .dmg?
.dmg (Apple Disk Image) is a disk image format used on macOS to package file systems into a single mountable file. DMG files are commonly used to distribute macOS applications, archives, and installers, appearing to users as virtual disks that can be opened and browsed like physical drives.
This quick guide explains when to use .dmg files, how to open them on any device, and how to share them instantly with FileXhost.
When to use .dmg files
- You are distributing a macOS application outside the Mac App Store.
- You want a branded, mountable disk image that contains your app bundle, documentation, or installer.
- You need to package multiple files into a single macOS-friendly container with optional compression or encryption.
- You are creating backups or archives of folders or volumes on macOS.
How to open .dmg files
On macOS, double-clicking a DMG file mounts it as a virtual disk in Finder, showing its contents in a new window. Users typically drag the app bundle to the Applications folder from there. On Windows or Linux, DMG files are not natively supported but can sometimes be inspected with third-party tools. When you upload DMG files to FileXhost, they can be shared as downloadable macOS images that users open and mount on their Macs.
Algorithm details
DMG files encapsulate an HFS+, APFS, or other file system image plus optional compression and encryption layers. When mounted, macOS treats the DMG like a block device, exposing the contained file system to the user. Developers often configure DMGs with custom backgrounds, icons, and layout to present polished installation experiences.
Browser & platform support
- Desktop: Browsers download DMG files as binaries; they are opened by Finder on macOS after download.
- Mobile: Mobile operating systems do not support mounting DMG files; they can only store or forward them.
- OS: Only macOS provides native support for DMG mounting; other platforms rely on specialized tools for extraction or conversion.
Format comparison
| Feature | Details |
|---|---|
| DMG vs PKG | DMG is a container/disk image; PKG is an installer package. Many macOS apps distribute a DMG that contains either an app bundle or a PKG. |
| DMG vs ZIP | ZIP is a cross-platform archive format; DMG offers a more native macOS experience with mountable file systems and custom layouts. |
| DMG vs ISO | ISO images are common for optical media and cross-platform use; DMG is Apple-specific and better integrated into macOS. |
| Security | DMGs can be encrypted and signed, but users should still only open them from trusted sources. |
How to create dmg files
- Disk Utility: Use the macOS Disk Utility app to create DMG images from folders or volumes.
- Command Line: Use `hdiutil` to script DMG creation, compression, and signing.
- Build Scripts: Integrate DMG creation into macOS build pipelines for app distribution.
- Third-Party Tools: Use GUI packagers that design custom DMG layouts with backgrounds and shortcuts.
How to convert dmg files
- FileXhost: Host DMG files on FileXhost for distribution to macOS users via shareable links.
- Extraction Tools: Use tools to convert or extract DMG contents to other formats (ZIP, ISO) on non-macOS systems.
- hdiutil: Convert between DMG variants (compressed, read-only, read-write) or other disk image formats on macOS.
- Imaging Utilities: Some cross-platform imaging tools can mount or convert DMGs for inspection.
Advantages & disadvantages
Advantages
- Native macOS experience for distributing apps and assets
- Supports compression, encryption, and custom presentation
- Easy for users to understand drag-and-drop installation workflows
Disadvantages
- Apple-specific; not ideal for cross-platform distribution
- Requires macOS to mount and use effectively
- Custom DMG setups can add complexity to build pipelines
Tools & software
macOS Utilities
Disk Utility, hdiutil
Packaging Tools
Create DMG utilities, commercial installer/DMG designers
Cross-Platform Tools
7-Zip and similar tools (for partial extraction on non-macOS systems)
Frequently asked questions
How do I install an app from a DMG?
Open the DMG on macOS, then drag the app bundle (usually shown with an Applications shortcut) into the Applications folder. After copying, you can eject the DMG.
Can Windows open a DMG file?
Windows cannot mount DMG files natively. Some third-party tools can extract contents, but DMGs are intended primarily for macOS.
Should I ship my macOS app as DMG or PKG?
DMG is great for drag-and-drop installs and a polished first-run experience. PKG is better for more complex installs that need system-wide changes or managed deployment.
Why does macOS warn me when opening a DMG?
Gatekeeper and notarization checks protect users from untrusted software. Ensure your DMG and app are properly signed and notarized, and advise users to only open DMGs from trusted sources.
Technical specs
- File type
- Executable
- Extension
- .dmg
- MIME type
- application/x-apple-diskimage, application/octet-stream
- Compression
- Uncompressed
- Max file size on FileXhost
- Up to 25 MB per file on the free plan and up to 1 GB on Pro FileXhost accounts.
Share .dmg files instantly
Upload your .dmg file to FileXhost to get a clean, shareable URL in seconds. View the file in a modern browser, protect access with optional settings, and let others download it without any confusing ads or cluttered file pages.
Upload .dmg file