Note: this software is based on information contained in Approximating Formulas for the USCF Rating System.
See The USCF
Rating System for more 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 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
Note: K represents an estimate of player rating volitility. 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
number of prior games, number of games played in the current event, and 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 the calculation may not be correct when all prior games have
either been all wins or losses.