A golf handicap is a numerical measure of an amateur golfer's playing ability. It can be used to calculate a 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. Exact rules relating to handicaps can vary from country to country.
Determining a player's handicap
A handicap is calculated with a specific arithmetic formula that says, approximately, how much worse than par a player should be able to play. The United States Golf Association and the Royal and Ancient Academy of Golf Club of St. Andrews, Scotland, specify slightly different ways to perform this calculation for players in North America and in the rest of the world, respectively. The details of these calculations are presented below.
A golfer's net score is determined from his or her gross score (the number of strokes actually taken) by subtracting his or her handicap from the gross score. The net scores of all the competing golfers are compared and (generally) the lowest score wins.
A player's handicap is 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 USGA refers to this as the "average best" method. So in a large, handicapped competition, the golfer who shoots the best with respect to his or her abilities and the normal variations of the score should win.
While there are many variations in detail, handicap systems are generally based on calculating an individual player's playing ability from his or her recent history of rounds. Therefore, a handicap is not fixed but is regularly adjusted to increases or decreases in a player's scoring.
A golfer whose handicap is zero is called a "scratch golfer." A golfer whose handicap is 18 is called a "bogey golfer." It is possible to have a handicap below 0; these are referred to as 'plus' handicaps, and at the end of the round, a 'plus' handicap golfer must add his handicap to his score. A professional golfer plays off scratch, but has no actual handicap.
In the United States, handicaps are calculated using several variables: The player's scores from his or her most recent rounds, and the course rating and slope from those rounds. A "handicap differential" is calculated from the scores, using the course slope and rating, and the player's handicap differentials are used to calculate the player's handicap.
Course rating and slope
In the United States (and elsewhere) each officially rated golf course is described by two numbers, the course rating and the slope rating. The rating of a particular course is a number generally between 67 and 77 that is used to measure the average "good score" by a scratch golfer on that course. The slope of a particular course is a ratio generally between 105 and 155 that describes the difficulty of a course for a bogey golfer (defined above). These two numbers are used to calculate a player's handicap differential, which adjusts a player's score in relation to par according to the slope and rating of the course.
For each officially posted round, the player's handicap differential is calculated according to the following formula:
Handicap differential = (gross score − course rating) × 113 / (slope rating).
The differential is rounded to the nearest tenth.
The handicap index is then calculated using the average of the best 10 differentials of the player's past 20 total rounds, times 0.96. Any digits in the handicap index after the tenths are truncated. 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. Updates to a golfer's index are calculated periodically according to schedules provided by state and regional golf associations.
The handicap index is used with the course's slope rating to determine the golfer's course handicap according to the following formula:
Course Handicap = Handicap index * Slope Rating / 113. The course rating is not used to determine a course handicap. The result is rounded to the nearest whole number.
The course handicap is the number of strokes to be deducted from the golfer's gross score to determine the net score.
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:
Gross score: 85 Course rating: 69.3 Course slope: 117
Yields a handicap differential of 15.2. If this golfer's handicap index is 10.5, the course handicap would be 10.5 * 117 / 113 = 11, and the net score would be 85 − 11 = 74.
Gross score: 85 Course rating: 71.9 Course slope: 124
Yields a handicap differential of 11.9. If this golfer's handicap index is 10.5, the course handicap would be 10.5 * 124 / 113 = 12, and the net score would be 85 − 12 = 73.
Additionally, before making the above calculation, the gross score must be adjusted using the equitable score control table, which removes the effect of abnormally high individual hole scores by establishing a maximum score per hole depending on the player's handicap index. For example, a golfer with a course handicap of 20 through 29 can record a maximum of 8 strokes on any one hole for handicap calculation purposes only.
Calculating a score
The handicap is used to determine on which holes a player (or team) is granted extra strokes. These are then used to calculate a "net" score from the number of strokes actually played ("gross" score).
To find how many strokes a player is given, the procedures differ between in match play and stroke play. In match play, the difference between the players' (or teams') handicaps is distributed among the holes to be played. For example, if 18 holes are played, player A's handicap is 24, and player B's handicap is 14, then A is granted ten strokes: one on each of the ten holes identified by the handicap numbers 1 through 10 on the scorecard and no strokes on the remaining eight. If A's handicap is 36 and B's handicap is 14, A is granted 22 strokes: one on each of the 18 holes to be played, and an additional one on each of the four holes identified by the handicap numbers 1 through 4 on the scorecard.
The procedure in stroke play is similar, but each player's individual handicap (rather than the difference between two players' handicaps) is used to calculate extra strokes. Therefore, a player with handicap 10 is granted one stroke on each of the ten holes identified by the handicap numbers 1 through 10 on the scorecard and no extra strokes on the remaining eight. A player with a handicap of 22 is granted 22 strokes: one on each of the 18 holes and an additional one on each of the four holes identified by the handicap numbers 1 through 4 on the scorecard.
Example for the calculation of "net" results: Assume that A is granted one stroke on a par four hole and player B is granted none. If A plays six strokes and B plays five, their "net" scores are equal. Therefore, in match play the hole is halved; in stroke play both have played a "net" bogey (one over par). If both play five strokes, A has played better by one "net" stroke. Therefore, in match play A wins the hole; in stroke play A has played a "net" par and B a "net" bogey.
Let's say that we have four golfers, George, Paul, John and Ringo, of various abilities are in a competition against each other. Here are the players and their handicaps:
The course has the following slope and rating:
So, using the formulas above, here are their course handicaps (only the slope is used to determine the course handicap):
And, finally, here are their gross and their net scores:
Paul wins! He is the only one in the group that actually shot better than his handicap, so he deserved to win.