Convert LHA to TAR Online (Compressed Archive to an Uncompressed Tape Format)

A Compressed Japanese Format Meeting a Plain Unix Bundling Format

LHA — stored as .lha or .lzh — was created in 1988 by Haruyasu Yoshizaki, whose LHarc tool packaged files using LZSS-style dictionary matching combined with Huffman coding under the name LZHUF. TAR (Tape ARchive) is much older and comes from an entirely different tradition: it was designed in the early Unix era specifically to write a sequence of files, one after another with a small header before each, onto magnetic tape drives. TAR by itself applies no compression whatsoever — it only concatenates files together with metadata, which is a fundamentally different job than what LHA does.

Converting an LHA archive to plain TAR means decompressing every entry — typically packed with LHA's -lh5- method, an 8 KiB window using static Huffman tables — and then writing that same decompressed data into TAR's simple sequential format with no compression applied at all. The resulting .tar file will, in almost every real case, be larger than the original LHA archive, sometimes considerably so, because TAR's job here is only to bundle files, not to shrink them.

Why TAR Carries No Compression by Design, Not by Accident

TAR's format is intentionally minimal: each file gets a 512-byte header recording its name, size, permissions, and modification time, followed by the file's raw data padded out to a multiple of 512 bytes. There's no method field, no dictionary, no entropy coding step anywhere in that structure — TAR was built to reliably write and read a stream of files to sequential media like tape, where a fixed, simple, block-based layout mattered more than saving space. Compression was always meant to be handled by a separate tool layered on top, which is exactly why "tar.gz" and "tar.bz2" exist as combined extensions, rather than TAR ever growing built-in compression of its own.

LHA, by contrast, was built from the start as a compression tool first — its method tags (-lh0- through -lh7-) each describe a specific compression approach, from no compression at all up to a 64 KiB sliding window with static Huffman coding. Converting from LHA to plain TAR is therefore a conversion that actively removes compression rather than changing which compression method is used, which is a distinct and important difference from converting LHA into another compressed format like 7z or ZIP.

This makes an LHA-to-TAR conversion unusual compared with most archive conversions covered elsewhere, since almost every other target format in common use today — 7z, ZIP, RAR, tar.gz, tar.bz2 — keeps some form of compression active. Choosing plain, uncompressed TAR as the destination is typically a deliberate decision, made because whatever happens to the files next, such as re-compressing with a different, more current algorithm or simply archiving them onto a system that reads TAR natively, benefits more from starting with an uncompressed, easily inspected bundle than from re-wrapping LHA's older compression inside a new container.

What Actually Changes Going From LHA to Plain TAR

• Lose — the compression LHA already applied: plain TAR stores files raw, so the resulting archive is typically larger than the original LHA file, sometimes by a wide margin.
• Gain — a format with no encoding complexity to fail: TAR's fixed 512-byte header blocks are simple enough that essentially every Unix-like system can read and write them without any special library.
• Gain — a natural fit for further piping into current compressors: a plain TAR file can be immediately fed into gzip, bzip2, or any other compressor as a separate step, which is exactly how tar.gz and tar.bz2 archives get built.
• Lose — LHA's narrow legacy compatibility: Amiga programs and old Japanese-market software expecting .lha or .lzh files won't recognize a .tar file at all.
• Gain — native support on every Linux and macOS system: the tar command ships as a standard utility on essentially all Unix-like operating systems, unlike LHA, which needs a specific separate tool.
• Lose — a single self-contained compressed file: a plain TAR archive isn't smaller than its contents the way the original LHA file was, so extra steps or extra tools are needed to shrink it back down again.
• Gain — straightforward inspection of raw contents: a plain TAR file's fixed 512-byte header blocks are simple enough to parse or scan manually, without needing to understand LHA's method tags or header-level variations first.

Where TAR Opens Natively and Where LHA Needs Extra Software

The tar command is a standard, pre-installed utility on essentially every Linux distribution and on macOS, since both are Unix-based systems that inherited TAR directly from that lineage. Windows added native tar command-line support starting with Windows 10's 2018 update, meaning a plain .tar file can now be extracted from the Command Prompt or PowerShell on a modern Windows system without installing any third-party program at all.

LHA has no equivalent built-in path on any of these systems. Windows has never included native LHA/LZH support in File Explorer, and the standard release of 7-Zip doesn't include it either, despite it being a long-requested feature on the project's own support forum. PeaZip is one of the few current archivers that lists LHA/LZH directly among its supported formats, and WinRAR can extract (though not create) LZH files. Between the two formats in this conversion, TAR is by far the one requiring no extra installation on a current system, while LHA is the one that does.

Real Complaints That Come Up Converting Old LHA Files to TAR

The most common surprise is the resulting .tar file being noticeably larger than the original .lzh archive — this isn't a conversion error; it's the direct, expected consequence of TAR applying no compression at all while LHA's -lh5- or similar method actively shrank the data. People expecting a like-for-like archive swap are often unprepared for how much bigger the plain TAR version turns out to be, especially with text-heavy or code-heavy source content that compresses well under LHA's Huffman-based methods.

A second recurring issue traces back to the source LHA file itself: garbled filenames after extraction, caused by archives built on Japanese-locale systems storing names in Shift-JIS encoding, which a tool assuming a different default encoding will misread. Fixing the filenames at the extraction stage, before writing the plain TAR file, is necessary — a TAR archive built from already-garbled names will simply preserve that same problem going forward.

A third, more serious concern applies to old, unmaintained LHA extraction software specifically: documented vulnerabilities (CVE-2004-0234 and CVE-2004-0235) let a maliciously crafted LHA archive trigger a buffer overflow or write files outside the intended extraction directory in the Unix lha tool through version 1.14. Extracting an untrusted, old LHA file with current, actively patched software, rather than a decades-old copy of the original tool, avoids that specific, long-documented risk before converting anything to TAR.

LHA and Plain TAR Compared

Questions About Turning LHA Archives Into TAR Files

Why is my converted TAR file bigger than the original LHA archive?
Because plain TAR applies no compression at all, while LHA's method tags, most commonly -lh5-, already shrank the data. Converting from a compressed format to an uncompressed one always increases size, and this is expected, not an error.

Should I compress the TAR file afterward?
That's the standard next step if smaller size matters — piping the plain TAR file into gzip or bzip2 produces a tar.gz or tar.bz2 archive, which is exactly the combined format most Linux software distributes in.

Can Windows open a .tar file without installing anything?
Yes, starting with Windows 10's 2018 update, which added a native tar command usable from Command Prompt or PowerShell, no separate program required.

Why won't my LHA file open before I can convert it?
Because neither Windows nor the standard 7-Zip release includes native LHA/LZH support. A specific tool like PeaZip, which lists LHA/LZH among its supported formats, needs to be installed first.

Does TAR preserve Unix file permissions the way LHA might not?
Yes — TAR's header format was built specifically for Unix systems and records ownership and permission bits directly, which is part of why it remains the standard packaging format for source code and system backups on Linux and macOS today.

Is there any reason to skip compression entirely and use plain TAR?
Yes, when the files are about to be compressed again with a different, more modern algorithm, or when they need to be inspected, edited, or reassembled before a final compression pass — starting from an uncompressed TAR bundle avoids working through LHA's older method tags twice.