7Z (7-Zip) Format Guide

Available Conversions

About 7Z (7-Zip) Format

7Z is the native archive format of the 7-Zip compression utility, created by Igor Pavlov in 1999. The format uses the LZMA2 (Lempel-Ziv-Markov chain Algorithm 2) compression method by default, which consistently achieves the highest compression ratios among popular archive formats. 7Z is an open-source format distributed under the LGPL license, making it completely free for both personal and commercial use without any licensing restrictions or royalty payments.

History of 7Z

Igor Pavlov developed 7-Zip and the 7Z format in 1999 as a free, open-source alternative to commercial archivers like WinZip and WinRAR. The format was designed from the ground up to achieve maximum compression ratios using the LZMA algorithm, which Pavlov also developed. LZMA (Lempel-Ziv-Markov chain Algorithm) improved upon the LZ77 algorithm by adding Markov chain probability models and range coding, resulting in significantly better compression than the Deflate algorithm used by ZIP and gzip. In 2009, LZMA2 was introduced as the default 7Z compression method, adding multi-threaded compression support and improved handling of incompressible data. The 7-Zip project has been continuously maintained for over 25 years, with the software downloaded billions of times and consistently ranked as one of the most popular free utilities on Windows. In 2022, an official Linux version of 7-Zip was released alongside the existing p7zip port, and ARM64 filter support was added for improved compression of ARM-based executables.

Key Features and Uses

The 7Z format's signature feature is solid compression, which treats multiple files as one continuous data stream rather than compressing each file independently. This approach dramatically improves compression for collections of similar files — a folder of source code files or documents might compress 40-60% smaller in solid mode compared to per-file compression. 7Z supports multiple compression methods (LZMA2, LZMA, PPMd, BZip2, Deflate) and allows different methods for different files within the same archive. AES-256 encryption provides military-grade security with the unique option to encrypt filenames, hiding even the directory structure from unauthorized access. The format supports dictionary sizes up to 1536 MB, self-extracting (SFX) archive creation, and multi-volume splitting for distributing archives across size-limited storage. 7Z archives can also include CRC-32 or SHA-256 checksums for integrity verification of every file.

Common Applications

7Z is widely used for software distribution where download size is critical — many open-source projects, game mods, and portable applications use 7Z to minimize download times. The format excels at archiving large datasets, source code repositories, and document collections thanks to solid compression. Enterprise environments use 7Z for encrypted backups and secure data transfer with AES-256 protection. The gaming community extensively uses 7Z for ROM collections, texture packs, and mod distributions where compression efficiency directly impacts hosting costs. Developers use 7Z to create self-extracting installers that recipients can run without needing 7-Zip installed. The XZ compression format (used by the Linux kernel and most Linux distributions) shares 7Z's LZMA2 algorithm, demonstrating the widespread trust in Pavlov's compression technology across both Windows and Linux ecosystems.

Advantages and Disadvantages