What is LHA? LZH Compression and Archive Format Explained
A 1980s freeware compression format and utility once popular in Japan and DOS gaming.
Last updated:
What is LHA?
LHA is a freeware compression utility and the associated archive file format created in 1988 by Haruyasu Yoshizaki. Archives produced by it commonly carry the .lzh or .lha extension, and the format is often referred to simply as LZH.
The tool was originally named LHarc and went through several renames before settling on LHA to avoid conflicting with the MS-DOS 'LH' load-high command. Its compression combines a variant of the LZ77 dictionary method known as LZSS with Huffman coding to reduce the size of the encoded output.
How LHA Works
LHA compresses each archive member independently, applying LZSS dictionary matching followed by Huffman coding of the resulting literals and match references.[1] Several method identifiers, such as -lh5- and -lh7-, denote different dictionary sizes and encoding parameters, and each file entry records its own method, original size, and CRC for integrity checking.[2]
History
Haruyasu Yoshizaki released the tool in 1988, initially as LHarc; it was renamed through LHx and LHA partly to avoid clashing with the MS-DOS LH (load-high) command.[1] The format and source were placed in the public domain, which encouraged numerous independent implementations.[1]
Legacy and Limitations
LHA was widely adopted in Japan and on the Amiga, and the Amiga's installation disks historically used it.[1] Today it is largely historical, and the multiplicity of header levels and method variants means some old archives are best handled by tools specifically aware of the format's quirks.[2]
MKV Technical Specifications
LHA vs Other Archive Formats
| Feature | LHA | ZIP | RAR |
|---|---|---|---|
| Compression algorithm | LZSS + Huffman[1] | DEFLATE | Proprietary |
| Open/proprietary | Open / freeware[2] | Open | Proprietary |
| Era | Late 1980s[1] | 1989 | 1993 |
| Current use | Legacy | Widespread | Common |
| Best for | Retro / Amiga files | General sharing | Multi-volume archives |
LHA is now largely legacy, while ZIP and RAR remain in active everyday use.
Advantages & Disadvantages
Advantages
LHA was released as freeware with documented internals, encouraging wide adoption and reimplementation.
Its LZSS plus Huffman approach delivered competitive compression on 1980s and 1990s hardware.
Versions and clones exist for DOS, Amiga, Unix, and other systems.
The utility was lightweight enough to run well on the limited machines of its time.
Disadvantages
It has been displaced by ZIP, 7z, and other formats outside of legacy and archival contexts.
Older LHA decompressors have a history of vulnerabilities, and the format is no longer actively maintained.
Native support is uncommon in current operating systems and requires dedicated utilities.
Common Use Cases
LHA is now encountered mainly in legacy and regional archival settings.
Japanese legacy archives | FileFormer
LZH remained widely used in Japan into the 2000s and persists in older Japanese software distributions.
Retro computing | FileFormer
Amiga and DOS software collections, including some game installers, were distributed as LHA archives.
Digital preservation | FileFormer
Archivists decompress historical LZH files to recover vintage software and documents.
Convert LHA Files Free
Use our free online archive converter to convert LHA and other formats - no signup, no watermarks.
Try Archive Converter FreeFrequently Asked Questions
What is the difference between LHA and LZH?
They refer to the same thing. LHA is the name of the utility, and .lzh and .lha are the common extensions for the archives it produces.
Who created LHA?
It was created in 1988 by Haruyasu Yoshizaki, a Japanese developer, originally under the name LHarc.
What compression does LHA use?
It combines LZSS, a variant of LZ77 dictionary compression, with Huffman coding.
Is LHA still safe to use?
It is best treated as a legacy format. Some older decompressors have known vulnerabilities, so caution is advised with untrusted archives.
Why was LHA popular in Japan?
It was free, well documented, and handled Japanese-language software distribution well, so it remained common there into the 2000s.