From the FAQ: How is a user's karma calculated? Roughly, the number of upvotes on their stories and comments minus the number of downvotes. The numbers don't

From the FAQ: How is a user's karma calculated? Roughly, the number of upvotes on their stories and comments minus the number of downvotes. The numbers don't match up exactly, because some votes aren't counted to prevent abuse. --- Obviously, to stop people gaming the system, Dang & co don't really want to go into the specifics. I do recall some older posts and some blogs that have analysed it heavily though, so a bit of Googling may help you. On a side note, I crossed the 500 karma points boundary yesterday, and I am relishing my new down-voting power! ;)