Theorycraft Request: Spreadsheed that compares Dex amount to variable amounts of Crit Damage / Chance

Like the title says, I'm terribad at math and more complex theorycrafting; with crit chance and damage becoming to some extent the stats de jour, I'm having a hard time trying to compare gear pieces where I may be sacrificing some or all dex on an item for certain increases in crit damage / chance. It'd be nice to have a simple spreadsheet to make this easier, I'm sure I'm not the only one who'd appreciate such help.