A golf handicap is a numerical measure of an amateur golfer's playing ability. It's intended to show a player's potential, not their average score, as is the common belief. A player will play to their handicap less than 25% of the time. The handicap index is calculated using the average of the best 10 differentials of the player's past 20 total rounds, times 0.96. If a golfer has at least 5 but fewer than 20 rounds posted, the index is calculated using from one to nine differentials according to a schedule.