How the Golf Handicap Calculator Works
A golf handicap lets players of different skill play fairly against each other. The World Handicap System, used by golf associations around the world, gives each round a score differential, averages your best differentials into a Handicap Index, and changes the index into a Course Handicap for the course you play. This calculator follows these steps.
Step 1: the score differential of a round
score differential = (adjusted gross score - course rating - PCC) x 113 / slope rating
- Adjusted gross score: your score for 18 holes, with the highest score on each hole set to net double bogey (par + 2 + the strokes you get on the hole).
- Course rating: the score that a scratch golfer is expected to make. It is printed on the scorecard, for example 72.0.
- Slope rating: the difficulty of the course for an average golfer compared with a scratch golfer. It goes from 55 to 155, and 113 is average.
- PCC (optional): the playing conditions adjustment, from -1 to +3. It corrects for weather and course conditions on the day.
The differential is rounded to one decimal. Example: an adjusted gross score of 88 on a course rated 72.0 with a slope of 113 gives (88 - 72.0) x 113 / 113 = 16.0.
Chart: the same score on courses with a different slope
A score of 88 on a course rated 72.0. A harder course (a higher slope) makes the same score count for more. Each block is 0.5.
Slope 100 ████████████████████████████████████ 18.1 Slope 113 ████████████████████████████████ 16.0 Slope 125 █████████████████████████████ 14.5 Slope 140 ██████████████████████████ 12.9
Step 2: the Handicap Index
Your Handicap Index is the average of the best differentials of your most recent rounds. When you have 20 rounds, it is the average of the lowest 8. With fewer rounds, fewer differentials are used, and for very few rounds a small adjustment is made:
| Rounds | Lowest differentials used | Adjustment |
|---|---|---|
| 3 rounds | 1 | -2.0 |
| 4 rounds | 1 | -1.0 |
| 5 rounds | 1 | 0 |
| 6 rounds | 2 | -1.0 |
| 7 or 8 rounds | 2 | 0 |
| 9 to 11 rounds | 3 | 0 |
| 12 to 14 rounds | 4 | 0 |
| 15 or 16 rounds | 5 | 0 |
| 17 or 18 rounds | 6 | 0 |
| 19 rounds | 7 | 0 |
| 20 rounds | 8 | 0 |
The index is rounded to one decimal, and the highest possible index is 54.0. Example with 20 rounds: the lowest 8 differentials are 9.0, 9.5, 10.0, 10.0, 10.1, 11.0, 11.0 and 11.1. Their average is 10.2125, and the index is 10.2.
Chart: 20 rounds, with the 8 that count
Green bars with a star are the 8 lowest differentials, which make the index. Each block is 0.5.
Round 1 ████████████████████ 10.1 * Round 2 ████████████████████████ 12.0 Round 3 ██████████████████████ 11.0 * Round 4 ██████████████████████████ 13.0 Round 5 ████████████████████████████ 14.0 Round 6 ███████████████████ 9.5 * Round 7 ██████████████████████████████ 15.0 Round 8 ████████████████████████████████ 16.0 Round 9 ████████████████████████ 12.2 Round 10 ██████████████████████ 11.1 * Round 11 ████████████████████ 10.0 * Round 12 ███████████████████████████ 13.3 Round 13 █████████████████████████████ 14.4 Round 14 ███████████████████████████████ 15.5 Round 15 ██████████████████ 9.0 * Round 16 ████████████████████ 10.0 * Round 17 ██████████████████████ 11.0 * Round 18 ████████████████████████ 12.0 Round 19 ██████████████████████████ 13.0 Round 20 ████████████████████████████ 14.0
Only your best rounds count, so one bad day does not raise your index by much.
Step 3: the Course Handicap
Course Handicap = Handicap Index x slope rating / 113 + (course rating - par)
The result is rounded to a whole number. It is the number of strokes that you get on that course from that set of tees. Example: an index of 16.4 on a course with a slope of 125, a rating of 71.5 and a par of 72 gives 16.4 x 125 / 113 + (71.5 - 72) = 18.14 - 0.5 = 17.64, which is 18 strokes.
The same index gives a different Course Handicap on courses of a different difficulty. For an index of 16.4 on a course with a rating equal to par (each block is one stroke):
Slope 105 ███████████████ 15.24 = 15 Slope 113 ████████████████ 16.40 = 16 Slope 125 ██████████████████ 18.14 = 18 Slope 135 ████████████████████ 19.59 = 20
Chart: the scale of an index
Each block is one point of handicap, from 0 to 40. A lower number is a better golfer.
0 40 ████████████████████████████████████████ under 10 | 10-17.9 | 18-27.9 | 28 and more
Tips
- Use the numbers from the scorecard. The course rating and the slope are different for each set of tees, and for men and women.
- Post every round. An index needs your real, recent rounds, not only your good ones.
- Apply the maximum score per hole. An adjusted gross score is not your raw score.
- Nine-hole rounds have their own rules. This calculator is for 18 holes.
What this calculator does not include
- The extra rules of the World Handicap System: the cap that limits a fast rise of the index, the 'exceptional score' reduction, and the low handicap limit.
- Handicap allowances for match play or team games (for example 95% or 85% of the Course Handicap).
- An official Handicap Index. It must come from a golf club or a national golf association.
This tool is a guide to help you understand your game. Your golf club or association issues your official handicap.