Golf Handicap Index: Score Differential, Slope, and Course Handicap
October 29, 2026
A golf handicap lets players of different abilities compete fairly. Under the World Handicap System (WHS), each round produces a score differential: Differential = (113 ÷ Slope Rating) × (Adjusted Gross Score − Course Rating). Course Rating is the expected score for a scratch golfer, and Slope Rating (55 to 155, with 113 for an average course) measures difficulty for a bogey golfer relative to a scratch golfer.
A player shoots 90 on a course with a Course Rating of 71.2 and a Slope of 128. The differential is (113 ÷ 128) × (90 − 71.2) = 0.8828 × 18.8 = 16.6.
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Your Handicap Index is the average of the lowest 8 differentials out of your most recent 20 rounds (with fewer rounds, different counts apply). Suppose the best 8 differentials are 14.2, 15.0, 15.6, 16.1, 16.6, 17.0, 17.4, and 17.9. The sum is 129.8, and the average is 16.2. The index is expressed with one decimal and is portable between courses.
Using only the best rounds reflects potential, not the average performance. Adjustments cap rapid increases and limit exceptional scores.
| Step | Calculation | Result |
|---|---|---|
| Score differential | (113 / 128) x (90 - 71.2) | 16.6 |
| Best 8 differentials (sum) | 14.2 + 15.0 + ... + 17.9 | 129.8 |
| Handicap Index | 129.8 / 8 | 16.2 |
| Course handicap | 16.2 x (128 / 113) + (71.2 - 72) | 17.55, rounds to 18 |
Course Handicap
The Course Handicap is the number of strokes you receive on a specific course: Course Handicap = Handicap Index × (Slope ÷ 113) + (Course Rating − Par). With an index of 16.2, a slope of 128, a course rating of 71.2, and a par of 72: 16.2 × 1.1327 = 18.35, plus (71.2 − 72) = −0.8 gives 17.55, which rounds to 18 strokes. On an easier course (slope 113, rating 70, par 72), the same player would receive 16.2 − 2 = 14.2, or 14 strokes.
Net Scores and Match Play
In stroke play, net score = gross score − course handicap: 90 − 18 = 72. In match play, players give or receive the difference in course handicaps, with strokes allocated by hole stroke index. The WHS also has a maximum score per hole for handicap purposes (net double bogey).
Practical Notes
Post every eligible round, including from different courses. The index updates daily in many countries. Check the rules of your national association for details such as playing conditions adjustments. The figures here are illustrative.
Frequently Asked Questions
How is the score differential calculated?
(113 ÷ Slope) × (Adjusted gross score − Course Rating).
How is the Handicap Index determined?
The average of the best 8 of the last 20 differentials.
What is slope rating?
A measure of a course's difficulty for bogey golfers relative to scratch golfers.
What is the course handicap formula?
Index × Slope ÷ 113 + (Course Rating − Par).
What is net score?
Gross score minus course handicap.