Most Compressible Archive File

[Torongo]

I am doing a backup at the moment, and I need to do it in Archive Files. What archive file is the most compressible? I need to save as much space as possible, and have IZArc, which I find to be the best for zipping and unzipping files.

Thank You. =)

~Joshua~

 

[stpbby]

7zip has one of the best compression ratios. check out their website they have graphs that show their compression compared to others.