7Z vs DMG
A detailed comparison of 7-Zip Archive and Apple Disk Image — file size, quality, compatibility, and which format to choose for your workflow.
7-Zip Archive
Archives & Compressed7z uses the LZMA2 compression algorithm to achieve significantly better compression ratios than ZIP. It is open-source and supports strong AES-256 encryption.
About 7Z filesApple Disk Image
Archives & CompressedDMG (Apple Disk Image) is the standard disk image format on macOS for distributing software. It can contain a complete file system with compression and optional encryption, and supports internet-enabled auto-mounting for seamless app installation.
About DMG filesStrengths Comparison
7Z Strengths
- Outstanding compression ratio — typically 20–50% smaller than ZIP, 10–30% smaller than RAR.
- Completely free and open source.
- AES-256 encryption of both content and filenames.
- Supports enormous archives (16 exabytes).
- Multi-threaded compression on modern CPUs.
DMG Strengths
- Universal macOS distribution format since 1999.
- Compressed or encrypted variants available.
- Can be bootable (used by recovery and installer DMGs).
- Custom backgrounds and layout create polished installer experience.
- Preserves Mac-specific filesystem metadata (extended attributes, resource forks).
Limitations
7Z Limitations
- Not natively supported on Windows before Windows 11 23H2 or macOS — requires a separate tool.
- Slower compression than ZIP (though decompression is fast).
- No built-in recovery records like RAR.
- Less ubiquitous in email and casual sharing than ZIP.
DMG Limitations
- macOS-only — Windows and Linux need third-party tools.
- Proprietary container with limited public documentation.
- File sizes are often larger than equivalent ZIP or 7z.
- Opaque to most antivirus and malware-scanning pipelines.
Technical Specifications
| Specification | 7Z | DMG |
|---|---|---|
| MIME type | application/x-7z-compressed | application/x-apple-diskimage |
| Compression | LZMA, LZMA2, PPMd, Bzip2, DEFLATE | UDCO (zlib), UDBZ (bzip2), UDZO (LZMA), ULMO (LZMA) |
| Max file size | 16 EB (exabytes) | — |
| Encryption | AES-256 (content + filenames) | AES-128 or AES-256 |
| License | LGPL | — |
| Extension | — | .dmg |
| Container types | — | UDIF (Universal Disk Image Format) |
Typical File Sizes
7Z
- Source code archive ~50% smaller than ZIP
- Linux distro installer 2–10 GB
- Virtual machine disk image 5–40 GB
DMG
- Small macOS app 5-30 MB
- Xcode installer ~12 GB
- macOS installer (full) 12-15 GB
Ready to convert?
Convert between 7Z and DMG online, free, and without installing anything. Encrypted upload, automatic deletion after 2 hours.
Frequently Asked Questions
7Z is an open-source archive format from the 7-Zip project. It uses the LZMA2 compression algorithm which achieves significantly better compression ratios than ZIP or RAR, making it ideal for archiving large files and datasets.
DMG (Apple Disk Image) is an archive format used to bundle multiple files and folders into a single compressed file. The archive preserves the directory structure and typically reduces total size via compression. DMG sits in the archives & compressed family and has specific strengths around compression ratio, speed, or platform support.
7Z files open with 7-Zip (free, Windows), PeaZip (cross-platform, free), Keka (macOS), and The Unarchiver (macOS). Windows does not natively support 7Z, so third-party software is required.
7-Zip, WinRAR, The Unarchiver (macOS), and the built-in archive utilities on Windows and macOS open most DMG files. For command-line extraction, 7z, unar, or the format-specific tool handles DMG cleanly. If your extractor does not recognise DMG, convert to ZIP first — ZIP opens on every operating system without extra software.
Use 7Z when maximum compression is the priority, such as software distribution and backups. Use ZIP when the recipient needs to open the file without installing extra software, since ZIP is natively supported everywhere.
Upload the DMG to KaijuConverter and pick ZIP, 7Z, TAR.GZ, or RAR as the target. Our pipeline extracts the original archive and re-compresses the contents into the target format. File permissions, timestamps, and directory structure are preserved where both formats support them.