Hello, and welcome to this Calculator. It will calculate, given the rating of the winner and loser, and the tournament K-Value, the ratings gain or loss to each player. It uses a clever mathematical function. The probability of winning is given by:
P = 1
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10^((Opponent's Rating-Player's Rating)/400) + 1
The winner's rating increases by R, and the loser's rating decreases by R, where
R = K × (1 - Pwinner)
If the match is drawn, then the player with higher rating loses D points, and the player with lower rating gains D points, where
D = K × (0.5 - Phigher player)
If you want to see how a particular match affected your rating, then type in your rating and your opponent's rating before the match, select the K-value from the list, and click Calculate.
*K-Value depends on the tournament you're attending. Apply these rules to determine the K-value of your tournament.