Recently I have cleaned up my files and folders which had accrued over more than 20 years. (Btw tools like AllDup and FileJuggler have been tremendously helpful). In the process I also compressed some larger folders using the open-source tool 7-ZIP.
That was the point where I asked myself which would be the best 7-ZIP compression settings to compress a typical “work” folder with some data, PDFs, Microsoft Office files, some images. Not that it would be necessary given how affordable storage has become, but nevertheless I wanted to know for lil’ Geek’s peace of mind.So what I did is this: I created a typical “office and work” folder which looks like this:
…and ran it through all 7z and ZIP compression profiles which are available in 7-ZIP. The result:
There are basically 3 tiers of speed vs. compression.
- Around 55% compression, there is no option but to use 7z, because ZIP just can’t compress the files that good, not anywhere near. The best preset here is “7z Normal”. You can save a little more space with “7z Maximum” or even “Ultra”, yet that comes with a hefty hit in terms of speed.
- Around 30% compression, there is not better preset than “7z Fastest”. Especially if compared to ZIP, you will get ~5 times the speed for exactly the same compression ratio. If you’re after the best compression in this tier, go for “7z Fast”.
- Finally there is “7z Save” and “ZIP Save”, which does not compress anything at all, but wraps files up into a single ZIP or 7z archive. Both of these options happen at full drive speed (here: ~2.5 GB/s), where 7z has a minimal advantage because the overhead data added to the archive file is marginally less compared to ZIP.
ZIP is the most widespread format out there, but compared to 7z (LZMA2) it is just inefficient. At only a fraction of the speed of 7z, you will get max. ~30% compression, while there is no way to get up to ~55% compression with ZIP at all. And even at 55% compression with “7z Normal” preset, 7z will be 50% faster than ZIP for ~30% compression performance. Yes, it is that clear.
Sure, there are other considerations to be taken into account, like compatibility (ZIP is surely most widespread, while you will need 7-ZIP to decompress 7z files), storage of error correction data (which 7z is not capable of, compared to i.e. WinRAR). But beyond those (obviously relevant) aspects, there is just no way around 7z today.