Being fairly new to this I also looked around and couldn't find any battle calculators to my liking. So after much research on formulas I came up with my own that has worked pretty well for me so far. I think it is fairly accurate, however I welcome anyone with more knowledge to check out the calculations and let me know if I messed up somewhere. Also if you have any questions or comments you can PM them or reply here.
https://docs.google.com/...V5UUllQ09rTi0xME9aaUFLdnc
It is in a spreadsheet format and I uploaded it to Google Drive as a Public document, so it can be viewed, but not edited. You would need to download your own copy via the File > Download as menu and choose what file type you want to save it as to edit/use it.
PS: I have the Chance multiplier set at 110% in addition to sending 110% over defense. So I am probably sending 120% over defense just to be safe, in case I made a small calculation error somewhere. Also, there are five copies of the same battle calculator because you can send out five brigades and sometimes I like to plan them all out first.
PPS: The Destock calculator page was thrown together in the past few days from input I could find on here and on the wiki, its kind of a work in progress still, so I welcome help me there as well if you have suggestions or comments!