Free online ISO to DMG converter

A macOS distribution workflow or disk-image tool may require a DMG instead of an ISO, although macOS can mount many ISO files directly. Conversion is useful for Mac-oriented packaging or storage, but it does not make a Windows, Linux, or optical-disc installer compatible with macOS.

What an ISO file is

An ISO is a disc-image file, usually representing the logical sectors and filesystem of a CD, DVD, or bootable installer. It is widely used by Windows and Linux publishers, system administrators, optical-media tools, and device vendors for operating-system installers, recovery media, firmware packages, and archived discs.

The .iso extension does not guarantee one filesystem or boot method. An image may contain ISO 9660, Joliet, UDF, El Torito boot records, or hybrid partition data; its contents and boot behavior come from the source image.

What a DMG file is

A DMG is an Apple disk-image container mounted by Finder, Disk Utility, and the hdiutil command-line utility. macOS software publishers commonly use it for application distribution, installers, encrypted archives, and virtual removable volumes.

DMG images can be read-only, compressed, writable, sparse, encrypted, and integrity-checked. A compressed read-only DMG usually reduces storage and transfer size when the source contains unused or repetitive data; it offers little reduction for data already compressed in archives, videos, or packages.

Direct conversion changes the image container, not the software inside it. It does not add a macOS application bundle, a Finder installer window, an /Applications shortcut, or Mac boot support.

Convert the file

For a browser-based conversion, upload the ISO to 101convert.com, select DMG as the output format, convert it, and download the result. Do not upload confidential images or media that must retain exact boot or sector-level behavior; use a local conversion for those files.

On macOS, hdiutil provides the most predictable local conversion. In Terminal, run:

hdiutil convert "/path/to/input.iso" -format UDZO -o "/path/to/output"

UDZO creates a compressed, read-only DMG. When the destination path has no extension, hdiutil normally creates output.dmg. Quote paths containing spaces.

Use an uncompressed read-only image when compression is not wanted:

hdiutil convert "/path/to/input.iso" -format UDRO -o "/path/to/output"

A writable container can be created with:

hdiutil convert "/path/to/input.iso" -format UDRW -o "/path/to/output"

A writable DMG does not make an ISO 9660 or UDF filesystem writable. To edit the files, create a new writable APFS or Mac OS Extended disk image in Disk Utility and copy the extracted source files into it. That process does not preserve the original disc layout or boot records.

Disk Utility can convert images through Images → Convert when it recognizes the ISO. Select the ISO, choose a compressed or read-only image format, and save the output. Use hdiutil when format selection, repeatability, or scripting matters.

Check the result and preserve compatibility

Mount and inspect the output before distributing it:

hdiutil attach -readonly "/path/to/output.dmg"

The command reports the mounted volume and disk identifier. Eject it in Finder or detach it with hdiutil detach /dev/diskN, replacing diskN with the reported identifier.

Run hdiutil verify "/path/to/output.dmg" to check DMG integrity when verification data is present. If the publisher supplies a SHA-256 or SHA-512 checksum for the ISO, verify the original before conversion; conversion cannot repair corrupted source data.

Keep the original ISO when it is needed for bootable USB creation, optical-disc burning, or a tool that explicitly accepts ISO or raw hybrid images. A converted DMG may mount correctly on macOS while remaining unsuitable for firmware booting or for Windows and Linux image-writing tools.