Read >>> WHAT IS A RATING

USCF National US Amateur Classes

Before a USCF tournament, player is either unrated, or has a rating based on having played games. A player's rating is termed ``provisional'' if it is based on 25 or fewer games, and is ``established'' otherwise. Assume the player competes in games during the event.

Post-event ratings are computed in a sequence of five steps:

• The first step sets temporary initial ratings for unrated players.
• The second step calculates an ``effective'' number of games played by each player.
• The third step calculates temporary estimates of ratings for unrated players only to be used when rating their opponents on the subsequent step.
• The fourth step then calculates intermediate ratings for all players.
• The fifth step uses these intermediate ratings from the previous step as estimates of opponents' strengths to calculate final post-event ratings.

Rating floors:  The absolute rating floor for all ratings is 100. No rating can be lower than the absolute rating floor.

A player with an established rating has a rating floor possibly higher than the absolute floor. Rating floors exist at 100, 1400, 1500, 1600, , 2100. A player's rating floor is calculated by subtracting 200 points from the highest attained established rating, and then using the floor just below. For example, if an established player's highest rating was 1941, then subtracting 200 yields 1741, and the floor just below is 1700. Thus the player's rating cannot go below 1700. If an established player's highest rating was 1588, then subtracting 200 yields 1388, and the next lowest floor is 100, which is this player's floor.

The magnitude of rating change in the rating formula depends not only on the player’s rating, but on the number of games completed previous to the event. The idea is that, for players who have completed a small number of games or who have a low rating, new tournament games should have a potentially large impact on their ratings.  Conversely, the rating changes for well-established players should be small.  Also, the formulas provides for a player who has an unusually strong performance, extra rating points awarded beyond the usual formula. This aspect of the formulas will help to track quickly improving players more accurately.

Read the details >>> The USCF Rating System.pdf