Introduction
A golf handicap is a numerical measure of an amateur golfer's playing ability. It can be used to calculate a so-called "net" score from the number of strokes actually played, thus allowing players of different proficiency to play against each other on equal terms. Handicaps are administrated by golf clubs or national golf associations.
Handicap systems are not used in professional golf.
Determining a player's handicap
While there are many variations in detail, all handicap systems are based on calculating an individual player's playing ability from his or her recent history of golf rounds. Therefore, a handicap is not fixed but is gradually adapted to any improvement or deterioration of a player's skills.
A player's handicap is (very roughly) equal to the average number of strokes that he or she plays above the par of a course. Thus, an expert golfer who plays a course in even par (scratch golfer) will have a handicap of 0. A player who constantly plays a 100 on a par-72 course will have a handicap of 100 - 72 = 28. Depending on countries, handicaps will start from between 28 and 54.
The par of each golf course can be said to be the number of strokes it would take a scratch golfer to complete a round in which two puts were taken on each green. In practice, it is often the case that courses are "easier" or "harder" than par, overall, to the amateur field. For this reason, a Standard Scratch Score (SSS) is used as a baseline for how the course plays in practice (e.g. an SSS lower than par indicates a course which golfers find slightly easier, and vice versa).
Akin to the SSS is the Competition Scratch Score (CSS). The principle is the same, only this describes how easy or difficult the course played during a given competition. It is against this CSS score that a player's handicap is adjusted by the club. Golfers with a handicap of 5 or lower are said to be Division 1 players. Higher handicap players are categorised as Division 2, 3, or 4. For every stroke the Division 1 golfer's net score is below the CSS, their handicap is reduced by 0.1. For Division 2 golfers, this figure is 0.2, for Division 3 golfers it is a 0.3 reduction, and 0.4 for Division 4 category golfers.
Similarly, amateur golfers are allowed a buffer zone to protect their handicap on "off-days". For Div 1 this is 1 stroke, for Div 2 this is 2 strokes, etc. This means that if a Division 1 golfer's net score is one stroke higher than the CSS, their handicap will not increase. If a golfer's net score is higher than the CSS plus buffer zone combined, their handicap will increase by 0.1. This 0.1 increase covers all golfers and does not vary by Division.
Course rating
In the United States (and elsewhere) each officially rated golf course is described by two numbers, the course rating and the course slope. For each posted round, the handicap differential is calculated according to the following formula:
Handicap Differential = (Gross Score - Course Rating) * 113 / (Course Slope).
The full handicap index is calculated using the average of the best 10 scores (using the formula above) of the past 20, times .96. Updates to a golfer's index are calculated monthly.
For example, the following table shows the impact of the same score at two different tee positions at the same course, and the resulting handicap differential:
Shoreline: White tees:
Gross score: 85 Course rating: 69.3 Course slope: 117
Yields a handicap differential of 15.16.
Shoreline: Blue tees:
Gross score: 85 Course rating: 71.9 Course slope: 124
Yields a handicap differential of 11.94.
When using this system, the gross score entered should conform to the rules of equitable score control, which puts a cap on the score per hole depending on the player's handicap index.
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