Whether you need to compress a few files, or the contents of an entire folder, then Windows is ready to help. Just select what you need, right-click, choose Send to > Compressed (zipped) folder, and it’ll build the zip file for you. Quick, easy and convenient – so do you really need anything more?

The authors of other archive tools, unsurprisingly, say yes. Programs like WinZip and 7-Zip boast many more features, including encryption, support for additional archive formats, and the ability to create self-extracting archives, for instance. But perhaps most importantly, they also claim to have far better compression algorithms, which means they can produce archive files that are much smaller than the competition. Sounds good – but is it really true? If we allowed WinZip, 7-Zip and Windows to compress the same sets of files, who would deliver the smallest sizes, and how much difference would there be?

To find out, we created three separate groups of test files.

The first consisted of 500 plain text documents, a little over 200MB in size. These should be very easy to compress, and we’d expect dramatic reductions in size.

The second was a mixed group: executable code, DLLs, OCXs, data files and more. Cutting these down to size would be more difficult, but good results were still possible.

And the third was the most challenging of all: 50MB of JPEGs. These are compressed already, so anything our archive tools could achieve would be welcome.

We then configured WinZip and 7-Zip to use their highest level of compression: the ZipX and 7-Zip containers, LZMA compression method, Ultra compression level, and so on. Then we compressed the three sets of files using both programs, and Windows – with interesting results.

The easy-to-compress Text group, for instance, saw dramatic reductions. Windows alone cut the file size from 206MB to under 40MB, a 19.3% compression ratio. But WinZip produced a 30MB archive, and a compression ratio of 14.1%. And 7-Zip managed an amazingly compact 17.3MB, an 8.4% compression ratio, effortlessly outstripping everyone else.

As we’d expected, compressing JPEGs was a far more difficult task, and no-one made a great deal of impact. Windows compression ratio was 96.4%, WinZip‘s a very similar 96.1%, and 7-Zip‘s a winning 95.7%, but even that only reduced our 50MB of files to a 47.8MB archive: nothing too spectacular.

Most of the time you’ll be compressing a combination of file types, though, and that’s what makes our Mixed group so interesting. And the results? Windows managed to compress our files by almost half (50.8%); WinZip did even better (44%); but once again, 7-Zip outpaced the competition, reducing our data to 39.3% of its original size.

This isn’t the entire story, of course – there are many factors you might want to consider before choosing an archive tool. Windows “compressed folders” may not offer the best compression, for instance, but it’s fast and easy to use. And WinZip is packed with useful features to encrypt, share, and back up your files.

If archive size is what matters most to you, though, the winner is clear: 7-Zip consistently delivers the smallest possible archives. Download the program now, and see what it can do for you.