In response to a couple of threads that have been hanging around the topic of armor vs. evasion, I started to create a simple spreadsheet (or at least it was meant to be. . .) to calculate defensive capabilities of your character in Path of Exile.
Given that the formulas used in PoE are slightly less simple than in many other such games, the sheet isn't as simple as it could be, but hopefully the information is useful, or at the very least interesting.
The spreadsheet is a googledocs spreadsheet - I think you need to be signed into google to access it, and you'll have to make your own copy to change numbers.
A few known issues/assumptions:
-Assumes no evasion entropy on crit chance
-Assumes total hp+es to avoid 1 shot, and total hp/2+es for 2shot (no es recovery between hits)
-I don't know the formula GGG uses to assign "default" accuracy for mobs or I would put it in the sheet. At the moment, you just have to guess. You can look at my other thread here for formulaic examples of how to probably get a default accuracy for mobs around your level. Essentially, enter your dodge rating on the sheet, then increase mob accuracy until you get an evasion chance that is something close to what your character sheet shows to get the default. Then, you want to increase it depending on mob type (except that we don't know the accuracy bonuses for blue/yellow mobs either!
-No support at all for chaos damage at the moment.. if you want to calculate something that does chaos damage, just replace one of the other elements that doesn't feature in the attack with chaos stats instead.
How to use it:
Enter your stats as they appear on your character sheet in the table, buffs/auras included (but without flasks applied). Enter any flask stats you want to test in the 2 flask slots on the right top - if the flask is an elemental resist. Enter monster stats you want to test in the bottom left, including setting attack type (attacks or spells, for evasion purposes).
What information will the sheet give you?
It will tell you:
-Basic physical damage required to 1 or 2 shot you (showing functionally what damage range you need for armor/evasion to be better for you given a particular incoming damage).
-Chance to dodge/block/avoid subsequent attacks, so as to find the inflection point at which armor becomes better again in the case of a 2 shot situation.
-Comparison of incoming damage states given a choice of flasks.
-What damage you can expect to receive per hit and per second, both crit and non crit.
-How RIDICULOUSLY overpowered endurance charges are for defensive purposes.
Let me know if you find any glaring mistakes - there are sure to be some.