How is a handicap determined?
A course “handicap” is determined from several factors. First, the course rating and slope are established indicating the difficulty of the course. Second, the standard slope of 113 is used. (This is the average slope established by the USGA.) Finally, the score “differential and index” are calculated using these figures and your “Adjusted Gross Score”. Therefore , your handicap will be:
Handicap “index” X 118/113 = Your handicap
Example: An index of 12.7 X 118/113 = 13 Handicap
What is an “Adjusted Gross Score”?
Your adjusted gross score is your actual score minus the “Equitable Stroke Control” amount for a score on a bad hole. The USGA has established the following table and strokes should be “adjusted” downward based on your handicap.
What is the handicap “Differential”?
A Handicap Differential is computed from four elements: Adjusted Gross Score, USGA Course Rating, 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 Slope Rating. Round the final number to the nearest tenth.
Handicap Differential = (Adjusted Gross Score - USGA Course Rating) x 113 / Slope Rating
The following is an example for determining a Handicap Differential using an Adjusted Gross Score of 82 made at ICC which has a USGA Course Rating of 69.2 and a Slope Rating of 118:
Adjusted Gross Score - USGA Course Rating: 82 – 69.2 = 12.8
Difference x Standard Slope Rating: 12.8 x 113 = 1446.4
Result / Slope Rating: 1446.4 / 118 = 12.26
Handicap Differential (rounded): 12.3
What is a handicap index?
The Handicap Index formula is based on the best Handicap Differential(s) in a player's scoring record. If a player's scoring record contains 20 or more scores, the best 10 Handicap Differentials of the most recent 20 scores are used to calculate the Handicap Index. As the number of scores in the scoring record decreases the percentage of scores used in a scoring record decreases from the maximum of the best 50 percent. If the scoring record contains 9 or 10 scores, 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 posted. A Handicap Index cannot not be calculated for a player who has returned fewer than five acceptable scores.
Twenty scores available. The following is an example of a Handicap Index calculation for a player with 20 scores.
Total of 10 lowest Handicap Differentials: 154.8
Average (154.8 / 10): 15.48
Average multiplied by.96: 14.861
Delete all digits after tenths: 14.8
Handicap Index: 14.8
Now multiply the index X the slope and then divide by 113
Ex: 14.8 X 118/113 = 15.4 (rounded to 15)
Handicap is 15
(It should be noted that an index with a decimal place of .5 or higher may or may not move a golfer to the next highest handicap due to the final formula established by the USGA)