I have shared a google doc spreadsheet as follows:
https://docs.google.com/spreadsheet/ccc?key=0AnvQX47NwSzDdEJqWUlhRDFaSzh3R3BVTkRZM1dqSFE#gid=0

This contains a calculator that does all the calculations for you.

What you can do:
1) Compare Vit equivalent of two items
2) Figure out how much Life changes if you change an equipment to another
- This works like in-game stats comparison function, only you don't need to have the item in your inventory for it to work
- This is mainly for comparing directly your current equipped item with potential upgrade from Auction House

You will only need to fill in information of:
1) Maximum HP (as shown in detailed character sheet)
2) Total Life Bonus (%)
3) Currently equipped item's Vitality & % Life (if any)
4) To be equipped item's Vitality & % Life (if any)
***ONLY fill in the yellow colored cells.

Bump for info sharing.

The vitality equivalent calculator looks like this:



Feel free to use/share it.
https://docs.google.com/spreadsheet/ccc?key=0AnvQX47NwSzDdEJqWUlhRDFaSzh3R3BVTkRZM1dqSFE#gid=0