DMG vs LZ4
A detailed comparison of Apple Disk Image and LZ4 Compressed — file size, quality, compatibility, and which format to choose for your workflow.
Apple 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 filesLZ4 Compressed
Archives & CompressedLZ4 is an extremely fast lossless compression algorithm focused on speed over compression ratio. It can compress at over 500 MB/s per core and decompress at multiple GB/s, making it the standard choice for real-time and in-memory compression.
About LZ4 filesStrengths Comparison
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).
LZ4 Strengths
- Decompression speed — approaches memcpy throughput.
- Very fast compression — can keep up with SSD write speeds.
- Stable format — reference implementation unchanged for years.
- Widely deployed in databases, filesystems, and kernels.
- BSD-licensed library.
Limitations
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.
LZ4 Limitations
- Compression ratio lags gzip by 20-30%.
- Not designed for long-term archival where ratio matters.
- Older than zstd, which beats LZ4 at comparable speed at slightly better ratio.
- Rare as a user-facing format — lives mostly inside databases and filesystems.
Technical Specifications
| Specification | DMG | LZ4 |
|---|---|---|
| MIME type | application/x-apple-diskimage | application/x-lz4 |
| Extension | .dmg | — |
| Container types | UDIF (Universal Disk Image Format) | — |
| Compression | UDCO (zlib), UDBZ (bzip2), UDZO (LZMA), ULMO (LZMA) | — |
| Encryption | AES-128 or AES-256 | — |
| Extensions | — | .lz4 |
| Algorithm | — | LZ77 variant with fast byte-level parsing |
| License | — | BSD 2-Clause (library), GPL v2 (CLI) |
| Typical integrations | — | Linux kernel, ZFS, Kafka, RocksDB, Cassandra |
Typical File Sizes
DMG
- Small macOS app 5-30 MB
- Xcode installer ~12 GB
- macOS installer (full) 12-15 GB
LZ4
- Text file 40-60% of original
- Already-compressed data (JPEG, MP4) 99%+ (no gain)
- Database page (typical) 55-70% of original
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Convert between DMG and LZ4 online, free, and without installing anything. Encrypted upload, automatic deletion after 2 hours.
Frequently Asked Questions
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.
LZ4 (LZ4 Compressed) 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. LZ4 sits in the archives & compressed family and has specific strengths around compression ratio, speed, or platform support.
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.
7-Zip, WinRAR, The Unarchiver (macOS), and the built-in archive utilities on Windows and macOS open most LZ4 files. For command-line extraction, 7z, unar, or the format-specific tool handles LZ4 cleanly. If your extractor does not recognise LZ4, convert to ZIP first — ZIP opens on every operating system without extra software.
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.
Depends on the goal. ZIP is the universal baseline — every OS extracts it out of the box. Formats like 7Z or TAR.GZ compress better but require specific tools. DMG may win on compression ratio, password support, or OS integration for specific workflows; ZIP wins on raw compatibility.