BZIP2 file format

.bz2 · .bzip2 · compression (single file) · introduced 1996 by Julian Seward

What is a BZIP2 file?

BZIP2, written by Julian Seward in 1996, compresses one file at a time using the Burrows-Wheeler transform followed by Huffman coding. It typically produces 10-15% smaller files than GZIP at the cost of being slower. Like GZIP, it is almost always paired with TAR (.tar.bz2) and is widely available on every Unix-like system.

Most readers reach this page after double-clicking a .bz2 file and finding their operating system unsure what to do with it. The good news: BZIP2 is a well-understood format with mature tooling on every major platform. It is supported in one click by mainstream archivers on Windows, macOS, and Linux.

How to extract a BZIP2 file

Opening a .bz2 file is straightforward on every modern operating system. The exact steps depend on which platform you are on:

On Windows

Locate the .bz2 file in File Explorer.
Right-click the file. If you have 7-Zip installed, choose 7-Zip → Extract Here. On Windows 11 the built-in extractor handles ZIP, 7z, RAR and several other formats directly through Extract All…
If prompted, pick a destination folder and click Extract.
The extracted files appear in a folder next to the original archive.

On macOS

Find the .bz2 file in Finder.
Install The Unarchiver from the Mac App Store, or Keka for both creating and extracting.
Right-click the file → Open With → The Unarchiver (or just double-click after Unarchiver is set as the default).
The extracted folder appears next to the archive.

On Linux

Use your file manager: right-click the archive → Extract Here (file-roller on GNOME, Ark on KDE).
On the command line, run one of:
```
bArchive Explorer2 file.bz2
```
The files appear in the current directory.

How to create a BZIP2 file

To pack files into a .bz2 archive, you typically need an archiver that supports writing this format. Not every tool can create every format — for example, only WinRAR can create real RAR files. The sidebar lists the software known to read and write BZIP2.

On the command line, the canonical create command is:

bzip2 file

If you regularly create archives at scale, a dedicated archive automation suite can wrap this command in scheduled jobs, integrity checks, and offsite replication.

Strengths

Better ratio than GZIP
Open and patent-free
Block-based — supports parallel decompression

Weaknesses and limitations

Slow compression and decompression
Single file only
Largely superseded by XZ and Zstd

Typical use cases

Source tarballs (.tar.bz2)
Linux kernel archives (historically)
Wikipedia database dumps

Technical details

BZIP2 uses the Burrows-Wheeler transform + Huffman algorithm and is identified on disk by the magic byte sequence 42 5A 68. The standard MIME type is application/x-bzip2. The format is an open specification and is free for any use.

Frequently asked questions

Is BZIP2 safe to open?

Archive files are containers — they are only as safe as what they contain. A .bz2 from a trusted source is fine; one received from a stranger can hold malicious executables, scripts, or files engineered to exploit bugs in your archiver. Always keep your archiver updated, and never run unknown executables that come out of an archive. A safe workflow is to extract into a sandbox and scan the contents before opening anything.

What is the maximum file size?

Modern implementations support archives in the multi-terabyte range. The practical limit is your filesystem (FAT32 caps at 4 GB; ext4, NTFS, APFS, and exFAT all comfortably handle multi-TB files).

Can I password-protect a BZIP2?

Not natively. TAR and the standard Unix compressors do not include encryption. Wrap the archive with GnuPG or age for confidentiality, or use a format like 7z that builds AES-256 in.

How does BZIP2 compare to other formats?

See our format comparison pages such as ZIP vs 7z, ZIP vs RAR, and tar.gz vs tar.xz for side-by-side feature tables.