Table of Contents

7-Zip Compression

More about 7-Zip Compression and comparison of compression formats in PowerArchiver

Introduction

7-Zip is the superior compression format featured in PowerArchiver. It is an open source format, providing open architecture and high compression ratio. It is also an modern format, that supports UNICODE filenames (so international users will not have any issues with special characters), maximum file sizes up to 16000000000 GB, and strong encryption (AES 256 bit). However, 7-Zip's greatest strength is that it is an open format - it is not forcefully controlled by any organization or individual, but an LGPL project that anyone can contribute to. Everyone can find and use latest DLLs and implement them into their application. This way it is impossible have a situation similar to ZIP format, where we have several different versions of ZIP files that not everyone can open in the same way, or such as with RAR, which is still not supported by some compression utilities due to its proprietary format. By its nature, everyone is encouraged to use 7-Zip in their applications with fairly liberal LGPL licensing.

Compression ratio

While most users will not understand nor care about what license a format distributed under, they will certainly care about the compression ratio that 7-Zip provides. 7-Zip mostly uses the LZMA compression method found in other formats, but with stronger compression settings and dictionary sizes which result in better (if slower) compression. 7-Zip also uses solid compression which enables a better compression ratio (same as with CAB and RAR). We have tested all formats found in PowerArchiver, as well as some other most popular formats that people use (RAR and ACE) in order to demonstrate compression strengths of 7-Zip.

Compression example

For our example of 7-Zip compression, we have compressed a Open Office 2 installation, which is a open source office suite. We have used a program installation because it is easy to show differences in compression ratios, but if you use any application you will notice similar results.

Notes

Things to know about 7-Zip (and its shortcomings)

Find out more about 7-Zip

7-Zip has been created by Igor Pavlov and is distributed under the LGPL. You can find out more about the 7-Zip format here. You can contribute to the 7-Zip open source project at Source Forge's 7-Zip project page.