What is LZH?

LZH (also known as LHA or LHarc) files use a compression algorithm combining LZSS (Lempel-Ziv-Storer-Szymanski) and adaptive Huffman coding. Created by Japanese developer Haruyasu Yoshizaki, LZH became the de facto standard compression format in Japan during the DOS and early Windows era. It was also widely adopted on Amiga computers for software distribution and file archiving.

LZH is now considered legacy but may be encountered when accessing Japanese retro software archives, old Amiga software collections, and vintage game distributions. The format was especially dominant in Japanese BBS and early internet file sharing. Modern archiving tools like 7-Zip can extract LZH files for compatibility with historical archives. Largely replaced by ZIP and RAR formats by the late 1990s.

Did you know? LZH was THE standard compression format in Japan, more popular than ZIP!

History

Haruyasu Yoshizaki developed LHarc/LHA as freeware, becoming massively popular in Japan and on Amiga platforms for efficient compression and ease of use.

Key Milestones

  • 1988: LHarc 1.0 released in Japan
  • 1991: LHA becomes Japanese standard
  • 1993: Peak usage in Japan/Amiga
  • 1996: Gradual ZIP migration
  • 2010: Development officially ended
  • Present: Legacy format archival only

Key Features

Core Capabilities

  • LZSS+Huffman: Dual compression
  • Good Ratio: Efficient for its era
  • Self-Extracting: SFX support
  • Japanese Support: Native character handling
  • Multi-Volume: Diskette spanning
  • Open Source: Free implementation

Common Use Cases

Japanese Archives

Retro Japanese software

Amiga Software

Classic Amiga distributions

Retro Gaming

Old game archives

Legacy Data

1990s file recovery

Advantages

  • Excellent compression for era
  • Native Japanese support
  • Open-source implementation
  • Amiga platform standard
  • Self-extracting archives
  • Historical significance
  • Still extractable today

Disadvantages

  • Completely obsolete format
  • Inferior to modern compression
  • Development ceased in 2010
  • Limited modern software support
  • Security vulnerabilities found
  • Only legacy use cases remain

Technical Information

Format Specifications

Specification Details
File Extension .lzh, .lha
MIME Type application/x-lzh-compressed
Compression LZSS + Huffman coding
Platform DOS, Amiga, early Windows
Status Discontinued (2010)
Origin Japan (1988)

Common Tools

  • Extraction: 7-Zip, WinRAR, PeaZip
  • Legacy: LHA.EXE (original), Amiga LHA
  • Modern: Total Commander, IZArc
  • Linux: lha package, unlzh