A USGA Handicap Index is a USGA mark that represents the potential ability of a player on a course of standard difficulty. Potential 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

a. Plus Handicap Differential

When the adjusted gross score is higher than the USGA Course Rating, the handicap differential is a positive number. Following is an example for determining a differential using an adjusted gross score of 95 made on a course with a USGA Course Rating of 71.5 and a USGA Slope Rating of 125:

Adjusted Gross Score - USGA Course Rating:     95 - 71.5 = 23.5
Difference x Standard Slope:     23.5 x 113 = 2655.5    
Result / USGA Slope Rating:     2655.5 / 125 = 21.244
Handicap Differential (rounded):     21.2

b. Minus Handicap Differential

When the adjusted gross score is lower than the USGA Course Rating, the handicap differential is a negative number. Following is an example for determining a differential using an adjusted gross score of 69 made on a course with a USGA Course Rating of 71.5 and a USGA Slope Rating of 125:

Adjusted Gross Score - USGA Course Rating:     69 - 71.5 = -2.5
Difference x Standard Slope:     -2.5 x 113 = -282.5
Result / USGA Slope Rating:     -282.5 / 125 = -2.26
Handicap Differential (rounded):     -2.3

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 less than 20.

The procedure for calculating Handicap Indexes is as follows:

(i) Use the following table to determine the number of handicap differentials to use;

Number of Differentials
Acceptable Scores To Be Used
--------------------------------------
5 or 6 Lowest 1
7 or 8 Lowest 2
9 or 10 Lowest 3
11 or 12 Lowest 4
13 or 14 Lowest 5
15 or 16 Lowest 6
17 Lowest 7
18 Lowest 8
19 Lowest 9
20 Lowest 10

(ii) Determine handicap differentials;
(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.

Example 1: 11 scores available.

Total of lowest 4 handicap differentials: 103.5
Average (103.5 divided by 4): 25.875
Multiply average by .96: 24.84
Delete digits after tenths: 24.8
Handicap Index: 24.8

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.

USGA USGA
Adjusted Course Slope Handicap
Date Score Rating Rating Differential
------------------------------------------------------
3/21/93 90 70.1 116 19.4
3/12/93 91 70.1 116 20.4
2/24/93 94 72.3 123 19.9
2/20/93 * 88 70.1 116 17.4
1/18/93 89 70.1 116 18.4
1/17/93 * 90 72.3 123 16.3
1/16/93 * 91 72.3 123 17.2
12/12/92 91 70.1 116 20.4
12/10/92 91 70.1 116 20.4
11/8/92 86 68.7 105 18.6
11/4/92 90 70.1 116 19.4
10/1/92 * 92 72.3 123 18.1
10/24/92 * 85 68.0 107 18.0
10/16/92 * 78 68.7 105 10.0
10/12/92 * 82 70.1 116 11.6
10/2/92 * 84 70.1 116 13.5
9/14/92 94 72.3 123 19.9
9/5/92 93 72.3 123 19.0
9/4/92 * 89 72.3 123 15.3
9/1/92 * 88 70.1 116 17.4

(*) = 10 scores with lowest handicap differentials


Total of 10 lowest differentials: 154.8
Average (154.8 / 10): 15.48
Average multiplied by .96: 14.861
Delete all digits after tenths: 14.8
USGA Handicap Index: 14.8

(vi) Apply Section 10-3 for golfers with two or more eligible
tournament scores.


10-3. Reduction Of USGA Handicap Index Based on Exceptional Tournament Scores


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 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.

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 Score -- An "eligible tournament score" is a tournament score contained within a player's scoring record. Tournament scores outside of the last 20 scores remain eligible for the calendar year in which they were made.

a. Purpose

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 tournament-score differentials that are at least three strokes better than the player's USGA Handicap Index calculated under
Section 10-2. Beginning in January 1994, this procedure shall not be used if more than five of the scores used to compute a player's USGA Handicap Index are eligible tournament scores.

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 tournament-score differentials 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.
(ii) Select the two lowest tournament-score differentials. 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 17.6 has three eligible tournament scores in his record. His two scores, which produce the lowest tournament-score differentials, are 82 and 83. They were made on a course with a USGA Course Rating of 70.6 and a Slope Rating of 130.

Tournament Score - Course Rating: 82 - 70.6 = 11.4
Difference x 113: 11.4 x 113 = 1288.2
Result / Slope Rating: 1288.2 / 130 = 9.9
Lowest Tournament-Score Differential: 9.9
2nd Lowest Tournament-Score Differential: (83 - 70.6) x 113/130 = 10.8

USGA Handicap Index under Section 10-2: 17.6
Second Lowest Differential: - 10.8
---------
6.8

Since 6.8 is greater than 3.0, continue.

(iii) Average the two lowest tournament-score differentials.
(9.9 + 10.8) / 2 = 10.35
(iv) Add the adjustment in the right-hand column of the following table, which is derived from the total number of eligible tournament scores, to the average computed in step iii. The resulting number is the player's USGA Handicap Index provided that it is at least one less than his USGA Handicap Index based on the Formula in Section 10-2.

Total Number of Eligible
Tournament Scores Adjustment
----------------------------------------
2 3.0
3 3.5
4 4.0
5 4.3
6 to 9 4.5
*10 to 19 5.0
*20 to 29 5.5
*30 to 39 6.0
*40 or more 6.5

*Note:The last four rows of the table will be effective January 1, 1994.

Example:

Average of Two Lowest Differentials: 10.35
Adjustment: 3.5
-------
13.85
USGA Handicap Index (rounded): 13.9

Since 13.9 is less than 17.6 by at least one, 13.9 becomes the player's new USGA Handicap Index.

c. Duration of Reduction

USGA Handicap Index reduction for exceptional tournament scores is calculated at each handicap revision. A player's USGA Handicap Index will return to the number calculated by the formula in Section 10-2 when his two lowest eligible tournament-score differentials are no longer more than three strokes better than his USGA Handicap Index calculated under Section 10-2.

d. Variation of Reduction

The Handicap Index based on this procedure and based on the same two tournament scores may vary depending on the number of tournament scores in a player's scoring record.

Example: Continued from 10-3b.

Revision 1 Revision 2
---------- ----------
Number of eligible tournament scores: 3 6

Average of two lowest tournament differentials: 10.35 10.35
Adjustment based on number of eligible tournament scores: + 3.5 + 4.5
------- -------
13.85 14.85
USGA Handicap Index (rounded): 13.9 14.9

Since the player posted three more eligible tournament scores in his scoring record before revision two, none of which were better than the previous two lowest differentials, his new USGA Handicap Index becomes 14.9 after revision two.

e. Handicap Committee Review of Reduction

The Handicap Committee shall review all reductions. The Handicap Committee may further reduce or override the reduction of a player's Handicap Index if his performance is not consistent with his scoring record. For example, the Handicap Committee may override reduction of the Handicap Index of a player who has returned 50 tournament scores, and whose Handicap Index reduction was based on early tournament scores.

f. Reporting Requirements

Authorized golf associations and computation service companies shall report any USGA Handicap Index reductions under this procedure (Section 10-3b) to the golf club and, if computational reports are provided to the golf association, the service company shall also report any Handicap Index reductions to the golf association.

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.