By default, 7-Zip creates 7z format archives with a
7z
. Each archive can contain multiple directories and files. As a
container format, security or size reduction are achieved using a stacked combination of filters. These can consist of pre-processors, , and encryption filters.The core .7z compression uses a variety of , the most common of which are , , and . Developed by Pavlov, LZMA is a relatively new system, making its debut as part of the 7z format. LZMA consists of a large LZ-based sliding dictionary up to 4 GB in size, backed by a The native 7z is open and . All are storedfound that the 7z compression is at least 17% better than
] and 7-Zip's own site reports that while compression ratio results are very dependent upon the data used for the tests, "usually, 7-Zip compresses to 7z format 30-70% better than to zip format, and 7-Zip compresses to zip format 2-10% better than most other zip compatible programsThe official 7z file format specification is distributed with the program's source code, in the 'doc' subdirectory