7z Format

7z is the new archive formatproviding high compression ratio.

The main features of 7z format:

• Open architecture
• High compression ratio
• Strong AES-256 encryption
• Ability of using any compressionconversion or encryption method
• Supporting files with sizes up to 16000000000 GB
• Unicode file names
• Solid compressing
• Archive headers compressing

7z has open architectureso it can support any new compression methods. Now the following compression methods are integrated to 7z:

7z also supports filters that improve compression ratio of main compression method. Now the following filters are integrated to 7z:

LZMA is default and general compression method of 7z format. The main features of LZMA method:

• High compression ratio
• Variable dictionary size (up to 4 GB)
• Compressing speed: about 2-8 MB/s on 4 GHz CPU (2 cpu threads version).
• Decompressing speed: about 30-100 MB/s on 4 GHz CPU (1 cpu thread).
• Small memory requirements for decompressing (depend from dictionary size)
• Small code size for decompressing: about 5 KB

7-Zip also supports encryption with AES-256 algorithm. This algorithm uses cipher key with length of 256 bits. To create that key 7-Zip uses derivation function based on SHA-256 hash algorithm. A key derivation function produces a derived key from text password defined by user. For increasing the cost of exhaustive search for passwords 7-Zip uses big number of iterations to produce cipher key from text password.

7z code is a part of 7-Zip program distributed under the GNU LGPL. You can download 7-Zip sources and binaries from Download Page.

Major part of 7z code is included to LZMA SDK.

Applications that support 7z archives: WinRARPowerArchiverTUGZipIZArc.

Links:

• 7z at Wikipedia

Copyright (C) 2026 Igor Pavlov.