Which ratings are used to calculate the new ratings?

I understand that some formula is used to calculate the players' ratings. But I don't know which ratings are used. Let's say at the beginning of the game between two players, the ratings of players A and B are respectively 1210 and 1199. Let's say when the game ends, the players' ratings are respectively 1190 and 1222 (player A's rating went down and player B's rating went up during the game (they were both playing other games while they were playing the game against each other). Which ratings are used to calculate the new ratings? The ratings they had at the beginning of the game or the ratings they had at the conclusion of the game? Or maybe I've got the whole ratings thing wrong?

Originally posted by Cleojuly
Which ratings are used to calculate the new ratings? The ratings they had at the beginning of the game or the ratings they had at the conclusion of the game?

The ratings used as a base of the calculation are the ratings at the moment when the game ends. Only that.
(If one or both are provisional players (not fulfilled 20 rated games) the calculation is somewhat different compared if you're a non-provisional.)

And that's correct. You can easily mis-use the calculation to blow up your rating to astronomical levels if you are cheat minded.

Originally posted by Cleojuly
I understand that some formula is used to calculate the players' ratings. But I don't know which ratings are used. Let's say at the beginning of the game between two players, the ratings of players A and B are respectively 1210 and 1199. Let's say when the game ends, the players' ratings are respectively 1190 and 1222 (player A's rating went down and pla hey had at the conclusion of the game? Or maybe I've got the whole ratings thing wrong?

FAQ

also, ratings are calculated when the game ends. wouldn't make much sense otherwise, as the games can last years.