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Rating Estimator (February 2023) Print E-mail
This is the current Rating Estimator, which uses the rating formulas in effect since February 1, 2023, when the bonus threshold was lowered from 14 to 12. This version of the Rating Estimator has a checkbox to select estimating the regular rating of high rated players (2200 or higher) in events at dual-rated time controls. (This setting does not affect players rated under 2200.)

Click Here
for a version of the Rating Estimator using the formulas in effect between June 2017 and January 2023.

This program lets you estimate how your rating has changed after playing in a tournament. The Ratings Estimator is a javascript application. Some older browsers do not support javascript. If the ratings estimator does not appear in your browser window, your browser may not be javascript compatible, or you need to enable javascript in your browser.

Enter the ratings (post-tournament if possible) of your opponents in any of the twelve boxes below, followed by your total score. Click on the performance button to see your estimated performance rating.

Your current rating is optional, but it is required if you wish to see your estimated new rating. We STRONGLY discourage players from using the ratings estimator to decide to withdraw from an event based on their estimated post-event rating, because the ratings estimator may be off by a point or two!

  Total Score
  Current Rating
# of Prior Games                       Age
Use Lower K values for high rated players (2200 and up) for estimating regular ratings in dual-rated events.

Note:  this software is based on information contained in Approximating Formulas for the US Chess Rating System.  See The US Chess Rating System for complete details.  

Note:  In the case of a perfect or zero score the performance rating is estimated as either 400 points higher or lower, respectively, than the rating of highest or lowest rated opponent.

Note:  you do not need to enter individual win, loss, draw results, only the total score (win=1.0, draw=0.5, and loss=0.0).  Click on the "New Rating" button to see your new estimated rating.  Click on "Show K" to see the "K" value (see below for details) used in the calculation.  Click on "Show Bonus" to see how much of your rating change was due to the bonus calculation. There are situations in which Bonus Points cannot be earned, the Ratings Estimator program does not have the information needed to take those situations into account.

Note: K represents an estimate of player rating volatility. The higher the value the more uncertain the prior rating is assumed to be, and therefore how rapidly a player's rating may change. Its value is determined from the number of prior games, the number of games played in the current event, and the prior rating.

Note: For unrated players with no prior games, set # of Prior Games to zero (Current Rating will be ignored). When all games are either lost or won, Age is used to estimate a prior rating. If no value is entered for Age, a prior rating of 750 is assumed.

Note: A current limitation is that the calculation may not be correct when prior games have either been all wins or all losses. Also, if a player has fewer than 9 games and is playing opponents more than 400 points higher or lower, the estimated ratings may not be very close to the actual computed ratings, because the Ratings Estimator doesn't have all the information it needs to duplicate the ratings formula.