see the help FAQ!!!
How is my rating calculated?
When you join, you are given a rating of 1200.
If you enter into a rated game, your rating will be recalculated on its completion so long as at least two moves have been made by each player.
Note: Until you have completed 20 games your rating may go down even when you win a game!
Until you complete 20 games, you will have a provisional rating. This rating is calculated as the average of all the games you have played. Each game is scored as being your opponent's rating (for a draw), your opponent's rating plus 400 (for a win), or your opponent's rating minus 400 (for a loss). If your opponent is also on a provisional rating, then the 400s above become 200s. If your opponent has played fewer than five games then their rating is treated as 1200 when calculating your rating.