change compression ratio of zipped files/make files smaller

I'm surprised  that "no" is the accepted answer to this as it shouldn't be.

Sure, in some circumstances - perhaps including yours - different zipping tools may only get you marginal differences in size, but  often that is not the case, so I wouldn't want people to read the incorrect 'no' answer and give up trying to compress files more.

ZIP files can be created with varying levels of compression, e.g. LOW, MEDIUM, HIGH, ULTRA (not all tools use these exact names for levels) and there can be a very large difference in the resulting files - for example HIGH compression might be literally twice as good as LOW!!

There are also alternative formats to ZIP, like RAR or 7z just to name two examples.  Why do these exist?  Well simply put some of the alternative formats are more effective than ZIP.  As an example on their home page 7-zip compress a 23mb series of files in different tools and found some formats are 50% better than others, even when both tools are set for maximum compression.

There are plenty of independent reviews out there which compare formats, search around a bit for a review if you are uncertain and definitely find a tool, I use free ones, that compress more.

No.  In general all file compression utilities give about the same result, the amount of compression you get depends on how compressible the files are. Pictures and videos are often about as compressed as they can get and since programs are essentially made of random data that doesn't compress well, they won't compress much further.

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I'm trying to compress files for easier upload, however the zip folder is only compressing the file by around 1MB, is there any way to compress the file more?

Sorry, but to be blunt this reply is utter rubbish - there are numerous examples online (and I have done plenty of tests on my own machine) that show that not all tools are equal, and different ratios can be achieved simply by changing the compression settings within the same app (normal, high, ultra compression), let alone between apps (7-zip being very notable)

As suggested by another poster - what you gain in size, you lose in compression time - but with the speed of processors these days that is pretty negligible.

I too would like to change the default compression ratio in windows 7 to 'ultra' or whatever the equivalent is, rather than install a different tool and I am sure it will be a simple registry setting somewhere.

Could someone with more experience/knowledge get back to us?

Thanks,

Nick.

No.  In general all file compression utilities give about the same result, the amount of compression you get depends on how compressible the files are. Pictures and videos are often about as compressed as they can get and since programs are essentially made of random data that doesn't compress well, they won't compress much further.

Really? I have a folder containing some source code and some DLL libraries. Zipping using the built in windows utility and 7-Zip using high compression, The result is a 10 MB difference. 20 MB compared to 30 MB. There are different compression algorithms and more aggressive compression techniques. The trade off is the speed at which it compresses and decompresses.

I'm sorry, but that's just plain wrong. Zips created by windows explorer use the deflate algorithm on medium setting, but you can go up to ultra with other programs (like 7z) and you can still open them in explorer, and it dose make a difference. there are also better algorithms for zip, but explorer cant handle them, and other formats can do even better. IMO 7zip on ultra is the best, unless you care about time, then it would be 7zip.