Chess Rating Systems - Harkness System

Harkness System

The Harkness System was invented by Kenneth Harkness, who published it in 1956. It was used by the USCF from 1950 to 1960 and by some other organizations.

When players compete in a tournament, the average rating of their competition is calculated. If a player scores 50%, they receive the average competition rating as their performance rating. If they score more than 50%, their new rating is the competition average plus 10 points for each percentage point above 50. If they score less than 50%, their new rating is the competition average minus 10 points for each percentage point below 50 (Harkness 1967:185–88).