USGA HANDICAP FORMULA
A Handicap Index is the USGA's mark which is used to indicate a measurement of a player's potential scoring ability on a course of standard difficulty. Potential scoring ability is measured by a player's best scores, and is expressed as a number taken to one decimal place. These scores are identified by calculating the handicap differential for each score. The USGA Handicap Index is calculated by taking 96 percent of the average of the best handicap differentials, and applying Section 10-3 for golfers with two or more eligible tournament scores.
10-1. How to Determine Handicap Differentials
A handicap differential is computed from four elements: adjusted gross score, USGA Course Rating, USGA Slope Rating and 113 (the Slope Rating of a course of standard difficulty). To determine the handicap differential, subtract the USGA Course Rating from the adjusted gross score; multiply the difference by 113; then divide the resulting number by the USGA Slope Rating. Round the final number to the nearest tenth.
Handicap Differential =
(Adjusted Gross Score - USGA Course Rating) x 113 /
USGA Slope Rating
10-2. USGA Handicap Index Formula
The USGA Handicap Index Formula is based on the best handicap differentials in a player's scoring record. If a player's scoring record contains 20 or more scores, then the best 10 handicap differentials of the most recent 20 scores are used to calculate his USGA Handicap Index. The percentage of scores used in a scoring record decreases from the maximum of the best 50 percent as the number of scores in the scoring record decreases. If the scoring record contains 9 or 10 scores, then only the best three scores (30 to 33 percent) in the scoring record will be used. Thus, the accuracy of a player's Handicap Index is directly proportional to the number of acceptable scores he has posted. A USGA Handicap Index shall not be issued to a player who has returned fewer than five acceptable scores. The following procedure illustrates how authorized golf associations and golf clubs calculate a player's Handicap Index if the number of acceptable scores in the player's record is fewer than 20.
The procedure for calculating Handicap Indexes is as follows:
(iii) Average the handicap differentials being used;
(iv) Multiply the average by .96; *
(v) Delete all numbers after the tenths digit. Do not round off to the nearest tenth.
*Note: Bonus for Excellence is the incentive that is built into the USGA Handicap System, for players to improve their golf games. It is the term used to describe the small percentage below perfect equity that is used to calculate Handicap Indexes (96%). As your Handicap Index improves (gets lower), you have a slightly better chance of placing high or winning a handicap event.
Example 2: The following is a sample scoring record of a player with 20 scores that shows how his USGA Handicap Index is calculated by a golf club or authorized golf association prior to applying Section 10-3.
A tournament score is a score made in a competition organized and conducted by a committee in charge of the competition. The competition must identify a winner(s) based on a stipulated round(s), and must be played under the principles of the Rules of Golf.
Using the above definition as a guideline, the committee in charge of the competition shall determine in advance if these conditions are met, and announce in advance whether the score shall be identified by the letter "T" when posted.
Routine events, such as regular play days, are not normally to be designated as T-Scores because they are not significant in the traditions, schedules, formats and membership of the club. Nine-hole scores are not to be designated as T-Scores.
Examples of inter-club competition scores that should be posted as tournament scores when they meet the above conditions are: team matches, competitions restricted by age, member-guest competitions, qualifying rounds for city, state and national competitions, and competitions conducted by golf associations.
Examples of intra-club competition scores that should be posted as tournament scores when they meet the above conditions are: low gross-low net competitions, four-ball match or stroke-play competitions, Stableford competitions, and club championships which are stroke or match play, scratch or with handicap.
Eligible Tournament ScoreAn eligible tournament score is any tournament score made either within the last 12 months, or within the player's current 20-score history.
The following procedure shall be used as an alternate calculation of a USGA Handicap Index for players with two or more eligible tournament scores. A player's Handicap Index will be reduced under this procedure when a player has a minimum of two eligible differentials for tournament scores that are at least three strokes (3.0) better than the player's USGA Handicap Index calculated under Section 10-2 and a value derived from the Handicap Reduction Table.
b. Determination of USGA Handicap Index Based on Tournament Scores
Apply the following steps to determine if there is a reduction in a USGA Handicap Index calculated under Section 10-2.
(i) Calculate the differentials for tournament scores by subtracting the USGA Course Rating from each eligible tournament score; multiply the result by 113, and divide by the USGA Slope Rating for each course played. Round the final number to the nearest tenth for tournament scores.
(ii) Select the two lowest differentials for tournament scores. Subtract the second lowest of these differentials from the player's current Handicap Index. Continue with the next step if the result is 3.0 or greater.
Example: A player with a USGA Handicap Index of 17.3 has three eligible tournament scores in his record. His two scores, which produce the lowest differentials for tournament scores, are 82 and 83. They were made on a course with a USGA Course Rating of 70.6 and a Slope Rating of 130.
Since 6.5 is greater than 3.0, continue.
(9.9 + 10.8)/2=10.35
(iv) Subtract that average from the player's Handicap Index.
(v) Using the number derived in step (iv) and the total number of eligible tournament scores in the player's scoring record, enter the Handicap Reduction Table (page 55) to determine the amount the player's Handicap Index is to be reduced.
(vi) Subtract the Table value from the player's 10-2 calculation. The result of that subtraction will be the player's USGA Handicap Index.
Continuation of the Example:
(i)T-Score Counter The number of eligible T-Scores will be counted on a revolving twelve-month basis. In order to keep track of the number, but not save every T-Score, a counter for each month is needed. The T-Score counter is the sum of the latest twelve monthly counters, plus any T-Scores older than one year that are a part of the twenty score history. The monthly counter will increase based on the date a score is processed, not the date of the score.
(ii) Best T-Score File Up to the best six eligible T-Scores are saved in a "Best T-Score File", separate from the golfer's handicap record of the latest 20 scores.
(iii) Adding T-Scores When a new T-Score is posted, it enters the golfer's normal handicap record, as a score and handicap differential. If the "Best T-Score File" has less than six eligible T-Scores in it, the new T-Score is added to that file. If the file already has six T-Scores, the new T-Score, if better than any T-Score in the file, is added to the file and the worst T-Score in the file is deleted from the file, regardless of the date of the T-Scores.
(iv) Discarding Old T-Scores At each handicap revision, each T-Score in the "Best T-Score File" is checked to see if the score is now older than one year or no longer part of the player's current twenty score history. If so, then the score is deleted from the file. Deleted T-Scores are replaced by the best eligible T-Scores (if any) in the golfer's handicap record that are not already in the "Best T-Score File".
d. Duration and Variation of Reduction
Additional Tournament Scores;
Expiration of T-Scores;
Variation in 10-2 calculation;
Fluctuation of 10-2 calculation in relation to the 2 lowest T-Scores.
10-4. Course Handicap
A player's Course Handicap is determined by multiplying his USGA Handicap Index by the USGA Slope Rating of the course played and then dividing by 113. The resulting figure is rounded off to the nearest whole number (.5 or more is rounded upward).
Optionally, Course Handicaps may be printed on handicap records and cards.
10-5. Nine-Hole Handicaps - Handicap Index (N)
For example, for an adjusted gross nine-hole score of 45 with a nine-hole Course Rating of 36.2 and a Slope Rating of 121, the nine-hole handicap differential is (45 - 36.2) x 113 / 121 = 8.2. If the average of the best ten nine-hole handicap differentials is 8.9, then the Handicap Index (N) is 8.9 x .96 = 8.5. It is written as "8.5N".
EQUITABLE STROKE CONTROL
*Note: The Double Bogey ESC procedure listed in the first row for 4 or less Course Handicaps is optional in 1998, but becomes mandatory January 1, 1999.
Example: A player with a nine-hole Course Handicap of 12 must adjust to a maximum number of 8, the score that he can post for any hole, regardless of par.
Note: A maximum USGA Handicap Index (N) will convert to a Course Handicap that exceeds these numbers on golf courses with Slope Ratings greater than 113.
A player may have a local handicap above these limits, but it shall be identified as a local handicap by the letter "J" following the number on a handicap card or report. (e.g. 24.5J) When such local handicaps are used for inter-club play, the USGA recommends that they be reduced to the maximum USGA Handicap Indexes (N) specified above.