Convert TAR.BZ to RAR Online (Bzip2 Tarball to a Proprietary Container)

What a .TAR.BZ Archive Is Made Of Going Into This Conversion

A ".tar.bz" file holds a tar stream compressed with bzip2, written with the compressor's suffix trimmed by one character from the fuller ".tar.bz2" spelling most tools and download pages actually use. Both name exactly the same data; the shortened form mainly turns up in scripts or listings that drop a trailing digit rather than in any separate compression scheme. The tar layer underneath does the file-bundling — recording each file's name, size, and permissions in its own header — while bzip2 compresses that entire concatenated stream in 900 KB blocks using a Burrows-Wheeler transform followed by Huffman coding.

Both the tar format and bzip2's compression algorithm are fully public and documented, and any developer can write software that creates them without asking anyone's permission. That openness is exactly what changes the moment the target format becomes RAR.

An Open Compression Algorithm Becoming a Legally Restricted One

RAR's compression algorithm is proprietary to RARLAB, the company behind WinRAR, and it has never been publicly published the way bzip2's or DEFLATE's algorithms have. The unRAR source code that lets other programs read and extract RAR archives is freely licensed for that purpose, but that same license explicitly forbids using it to reverse-engineer or recreate RAR's compression side — which is the specific, documented reason mainstream tools like 7-Zip and PeaZip can open a RAR file but cannot create one, under any build configuration, regardless of platform.

Converting a .tar.bz archive into RAR therefore always routes through WinRAR itself or RARLAB's own command-line rar tool — the only software actually licensed to write the format. Structurally, the conversion still follows the same basic path as any archive rebuild: bzip2 decompression exposes the plain tar stream, and the files inside it get handed to RAR's compression engine and repackaged using RAR's own container, which — like 7Z and unlike a bzip2 tarball — stores per-file metadata natively rather than depending on tar to do that job first.

The current RAR 5.0 format also supports recovery records built on Reed-Solomon error-correcting codes, letting a RAR archive repair a limited amount of internal damage on its own — a capability with no equivalent inside a plain bzip2-compressed tar stream, where a damaged block can, at best, be partially salvaged with a dedicated tool like bzip2recover rather than automatically reconstructed.

RAR 5.0 is also a genuinely different container from the earlier RAR 4.x line rather than just a version bump — it changed its internal block structure and raised the maximum number of volumes a split archive can use from 255 in RAR 4.x to 65,535. A converted archive built today by any current version of WinRAR defaults to the RAR 5.0 layout unless an older format is explicitly requested for compatibility with software that still expects RAR 4.x specifically.

What Rebuilding a Bzip2 Tarball as a RAR Gains and Costs

• Gain — optional self-healing via recovery records: RAR 5.0's Reed-Solomon-based recovery record can repair limited archive damage automatically, something a bzip2 tarball has no built-in equivalent for.
• Gain — native multi-volume splitting with up to 65,535 parts: RAR 5.0 supports far more volumes than the legacy RAR 4.x format's 255-part ceiling, useful for very large archives split across many pieces.
• Gain — password protection with full filename encryption: RAR archives can hide file names as well as contents, unlike a bzip2 tarball, which has no encryption feature of any kind built in.
• Lose — free creation rights: writing a RAR file always depends on RARLAB's own software; a bzip2 tarball can be built by any of dozens of free, independently developed tools.
• Lose — the open, inspectable compression format: bzip2's algorithm is fully published and can be audited or reimplemented by anyone; RAR's compression internals are not publicly documented.
• Unchanged — the files themselves: a straightforward rebuild doesn't touch file content, only which container and compression method holds it.

Who Can Actually Build a RAR File Versus Who Can Only Open One

WinRAR and RARLAB's command-line rar utility are the only software actually licensed to create RAR archives, available for Windows, macOS, and Linux, with WinRAR itself free to evaluate but formally shareware after its trial period. Extraction is a different story entirely: 7-Zip, PeaZip, The Unarchiver, and Windows 11's own File Explorer (starting with the 24H2 update, via its libarchive-based archive support) can all open and extract an existing RAR file without any licensing issue, since unRAR's extraction code is freely distributable — it's specifically creating new RAR data that stays restricted to RARLAB's own tools.

Bzip2 and tar, by contrast, ship by default on essentially every Linux distribution and macOS, and Windows has included a bzip2-capable tar.exe since Windows 10 build 17063 — no license, purchase, or trial period involved on either side of a .tar.bz workflow, which is a genuinely different distribution model from anything touching RAR's compression.

Real Problems Reported Converting Bzip2 Tarballs Into RAR

A frequent complaint on forums involves someone trying to create a RAR archive using a free tool like 7-Zip and discovering there's simply no "save as RAR" option anywhere in the interface — this isn't a missing feature or a bug to report, but a direct consequence of the licensing restriction on RAR creation; the documented resolution in every such thread is installing WinRAR or RARLAB's command-line tool specifically for that step.

A second recurring pattern involves WinRAR's trial period expiring, after which the program keeps working for extraction and even archive creation with a persistent reminder screen, since WinRAR doesn't hard-lock its features after the evaluation period — a detail that surprises people expecting a full stop, and one that's specific to WinRAR's own licensing model rather than to the RAR format itself.

A third documented issue shows up around recovery records: someone enables RAR's recovery-record protection expecting it to guard against any possible damage, then finds a badly enough corrupted archive still can't be repaired — Reed-Solomon recovery records are effective against a bounded amount of damage proportional to how much recovery data was added, not an unlimited insurance policy, and the practical fix reported in these threads is allocating a larger recovery record percentage for genuinely critical archives.

A fourth pattern involves someone receiving a RAR archive built with the older RAR 4.x format and a tool that only understands RAR 5.0 features, such as certain filename-encryption options introduced with the newer format — extraction still generally works across both, since RAR 5.0 readers handle RAR 4.x archives as well, but building or modifying an archive with format-specific options requires knowing which RAR generation the receiving software actually expects.

TAR.BZ and RAR Side by Side

Common Questions About Turning a TAR.BZ File Into a RAR

Why can't I create a RAR file with 7-Zip or PeaZip?
Because RAR's compression algorithm is proprietary, and the license covering the freely available unRAR code specifically forbids using it to build software that creates RAR archives. Only WinRAR and RARLAB's own tools are licensed to do that.

Is a .tar.bz file the same thing as a .tar.bz2 file?
Yes, in effectively all real cases — both describe a tar stream compressed with bzip2, just written with a shortened compressor suffix on the first.

Does RAR compress better than bzip2?
Results vary by content and by which compression method and settings are chosen; there's no universal winner, and RAR's exact algorithm isn't published in enough detail to make a precise general comparison the way bzip2's openly documented method allows.

Can I open a RAR file for free even if I can't create one?
Yes. 7-Zip, PeaZip, The Unarchiver, and Windows 11's 24H2-and-later File Explorer can all extract existing RAR archives at no cost, since the extraction-only unRAR code is freely licensed.

What happens to the recovery record if I keep editing a RAR archive?
Adding, removing, or otherwise modifying files inside a protected RAR archive typically invalidates its existing recovery record, since the record is calculated against the archive's specific current contents — a fresh recovery record needs to be generated after any change.

Does converting to RAR change the files inside the archive?
No. The underlying file data, extracted back out, comes out identical either way; only the container format and compression method wrapped around it change.