Skip to content

About 7-Zip Format


For further information, please visit

7z is an archive format, providing high compression ratio, by Igor Pavlov. Main features of the 7z format:

  • Open architecture

  • High compression ratio

  • Strong AES-256 encryption

  • Ability to use any compression, conversion or encryption method

  • Supporting files with sizes up to 16000000000 GB

  • Unicode file names

  • Solid compressing

  • Archive headers compressing

7z has open architecture, so it can support any new compression methods.

The following methods are integrated into 7z:

Method Description
LZMA Improved and optimized version of LZ77 algorithm
LZMA2 LZMA-based compression method. It provides better multithreading support than LZMA.
PPMD Dmitry Shkarin's PPMdH with small changes
BCJ Converter for 32-bit x86 executables
BCJ2 Converter for 32-bit x86 executables
BZip2 Standard BWT algorithm
Deflate Standard LZ77-based algorithm

LZMA is the default and general compression method of 7z format. Main features of LZMA method:

  • High compression ratio

  • Variable dictionary size (up to 4 GB)

  • Compressing speed: about 1 MB/s on 2 GHz CPU

  • Decompressing speed: about 10-20 MB/s on 2 GHz CPU

  • Small memory requirements for decompressing (depend from dictionary size)

  • Small code size for decompressing: about 5 KB

  • Supporting multi-threading and P4's hyper-threading

LZMA compression algorithm is very suitable for embedded applications. If you want to use LZMA code, you can ask for consultations, custom code programming, and required developer licenses at

External links for developers:

Technical Notes

7-Zip compression system of Paquet Builder is based on 7-Zip and LZMA SDK 19.0.

7-Zip Self-Extractors made with Paquet Builder do not support BZip2 nor Deflate methods because LZMA2, LZMA, BCJ/BCJ2 and PPMD are enough to achieve good compression ratios.