coan.net: Our FAQ says that ratings are based on the U.S. Chess Federation system.  But as far as I know, once one has an established rating in the USCF, the rating formula computes changes by ignoring any differences greater than 400 points between the ratings of the 2 opponents.  This used to have the effect of limiting rating changes to ±32 from any single game--even if I were to miraculously defeat Hikaru Nakamura...or were to lose a game to one of my cats (more likely, I think).