Ok, time for the expert....
A person's Soul weighs EXACTLY 15.23 grams.
This is based on the fact that once I extract it from said person, I have to peel away or "strip" vast quantities of a protective barrier or "Shield" to get to the Meat and Potatoes so to speak. Originally "out of the box" it's weight's vary. And the more good things a person has done in their life, the heavier it weighs. Now take me for example... SoulTakr, I don't have one, that's how I know and that is why I do what I do(feeding off all yous guys)
I hope that everyone is now satisfied w/ the correct answer and will look to me more often than "Ask Jeeves" or Google
Have a nice day