I posted this over on the official forums initially, and then my boyfriend suggested I post it over here as well.
It lets you compare weapons and armor for damage and EHP changes and provides stat weightings based off of dps gains per 1/1% to each stat (normalizations vs each dps stat are also calculated). There is also a cost/dps gain comparison section. Formulas should be accurate (within a 1% error margin for the limited testing I could do privately) for all classes, though I have had 1 report of monk dps being slightly off (unconfirmed if it is true beyond rounding errors).
In order to get a useable copy, while logged into a Google account, click File > Make a copy.
If you don't have a Google account, you can export to Excel or OpenOffice, but you will lose drop-down box functionality in the Class, Armor Slot, and Weapon Type input boxes (to work around this, you can just type in the proper inputs; for Weapon Type, follow the format on the Formulas Sheet from A10 to A28).
-Yellow boxes are input boxes
-Do not alter any other color box
-Do not change anything on the Formulas Sheet
-The passive bonus input section can be used to add any class-specific stat bonuses such as Ruthless or Follower buffs. Add one bonus to each box; monks and warriors can use the Armor input box here to simulate their dex/vit to armor conversion by simply entering their total dex or vit.
-When doing item comparisons, enter the stats of the new item in the corresponding boxes.
-Monk and Barbarian 30% passive damage reduction is already factored into the equations for those classes
-Dual-wield 15% attack speed bonus is automatically applied when appropriate.
-I tested damage numbers and mechanics for all skills/runes, but some I couldn't get numbers matched up properly. I welcome any insight into the formulas/math for any of the skills.
I had issues getting sheet numbers to match up with in-game numbers for the following skills:
Rain of Vengeance - unruned
Rain of Vengeance - Dark Cloud (I think I figured this one out; needs confirmation)
Rain of Vengeance - Anathema (I think I figured this one out; needs confirmation)
Caltrops - Jagged Spikes (I think I figured this one out; needs confirmation)
Smoke Screen - Choking Gas
-Added specific armor slots to make item comparisons easier to do
-Split Current Stats from Comparison Stats
-Added an Instruction Sheet
-Made the Formulas easier to follow for those who are interested in them
There's specific inputs for the weapon and off-hand that the calculations take into account already. I will mess with the setup for it though since I did overlook non-weapon off-hands in that regard, so that will take a bit of time. The cur_int problem is an easy fix though that I'll take care of right now.