Compression formats test.

While testing ExtractNow (review on File Utilities page), I thought it would be interesting to try the most popular compression formats, to see which gave the best compression.

The test folder to be compressed contained:

Program exe 2.7Mb.
Music wav files 1.94Mb
Text document 334k
Bitmap image 1.37Mb
Data file 2.05Mb
Html help file 914k
Pdf file 1.97Mb

Total = 11.2Mb

The formats I tested were, zip, 7-zip, cab, lzh, sqx and rar. The zip file was created using the built in XP zipper, the 7-zip file was created using the 7-zip File Manager (freeware), the rar file was created using WinRar (shareware) and TugZip (freeware) created the rest of the formats.

All the tests used the normal, or default settings, the results were:

Cab -- 6.17Mb
7-Zip -- 6.19Mb
Rar -- 6.34Mb
Sqx -- 6.72Mb
Zip -- 6.85Mb
Lzh -- 7.01Mb

As you can see the cab format performed best on the normal settings, although 7-zip was hot on its heels.
For the second test I used the maximum settings on 7-zip and rar (the cab format does not seem to have many extra settings). 7-zip does have an "ultra" setting, but this was so slow as to be unusable on my computer.
The results were:

7-zip -- 6.00Mb
rar -- 6.12Mb

7-zip easily beat rar, but when attempting to decompress non-standard 7-zip files, with programs other than the official 7-zip File Manager, I did have some reliability problems, whereas the rar files opened reliably every time.

It is possible to create self-extracting (Sfx) archives, this bypasses the problem of the file recipient not having an extraction program, or simply not knowing what to do with the file.
The only problem with making a file self extracting, is that it increases the file size, the files now become:

7-zip exe -- 6.12Mb. When created using TugZip, which has a better Sfx module this drops to 6.07Mb
rar exe -- 6.21Mb
cab exe 6.22Mb

So overall 7-zip does seem to have the best compression levels, but at the expense of reliability, when using any program other than the official 7-zip File Manager.
All the programs took considerably longer to compress files when using high levels of compression, which could be a problem if compressing very large files.
For files of less than 5Mb, the gain in file size is probably not significant enough, to use anything other than a standard zip file, but for larger files, a self-extracting 7-zip file is possibly the best choice, as it has the smallest file size, a simple extraction window and is more reliable in the Sfx format.
But if the reliability of 7-zip is a worry, a self-extracting rar, or cab file could be a better option.

TugZip site

7-Zip File Manager site

WinRar site

Rob Goldfish Web Site

Copyright 2005 Rob Goldfish.