# Golf handicap calculator (World Handicap System)

> Golf handicap calculator: World Handicap System Handicap Index from your score differentials (best 8 of 20), then course and playing handicap for any tee.

Interactive version: https://www.calcopenly.com/everyday/golf-handicap-calculator
Subject: Everyday calculators

The World Handicap System turns each round into a score differential: (113 ÷ Slope Rating) × (adjusted gross score − Course Rating − PCC), rounded to the nearest tenth. The Handicap Index is the average of the lowest 8 of your most recent 20 differentials. With 3 to 19 differentials, Rule 5.2a's table sets how many count and subtracts 2.0 or 1.0 when there are only 3, 4 or 6. The course handicap for a set of tees is Handicap Index × (Slope Rating ÷ 113) + (Course Rating − par).

The default 20 rounds give differentials from 10.4 to 19.7; the lowest 8 average 12.2125, so the Handicap Index is 12.2. On a course rated 71.8 with a slope of 131 and par 72, that is a course handicap of 14 and a playing handicap of 13 at the 95% stroke-play allowance.

Enter adjusted gross scores, each hole capped at net double bogey, or paste differentials from a handicap app. Exceptional score reductions are not applied, because they need your index as it stood on each day.

## Inputs

- **Start from** (options: My scores, My Handicap Index)
- **Rounds: score, Course Rating, Slope, PCC**: One 18-hole round per line, oldest first: adjusted gross score, Course Rating, Slope Rating and an optional PCC (−1 to +3). A line with a single number is read as a score differential.
- **Low Handicap Index (previous 365 days)**: Only for the soft and hard caps (Rule 5.8), which apply once you have 20 scores. Leave blank to skip them.
- **Handicap Index**: Type a plus handicap as a negative number: +2.1 is −2.1.
- **Course Rating of the tees you play**
- **Slope Rating**
- **Par**
- **Handicap allowance**: Rules of Handicapping Appendix C recommendations.

## Results

- Handicap Index — main result
- Differentials counted
- Average of those counted
- Rule 5.2a adjustment
- Index before the soft and hard cap
- Course handicap (strokes)
- Course handicap before rounding
- Playing handicap (strokes)

## Formula

$$
\begin{gathered}\text{SD} = \frac{113}{\text{Slope}}\,(\text{AGS} - \text{CR} - \text{PCC}) \\ \text{HI} = \overline{\text{lowest 8 of 20 SD}},\qquad \text{CH} = \text{HI} \times \frac{\text{Slope}}{113} + (\text{CR} - \text{par})\end{gathered}
$$

## Worked examples

### 20 rounds on three courses

- Start from: My scores
- Rounds: score, Course Rating, Slope, PCC: 88, 71.8, 131 / 92, 70.4, 124 / 85, 71.8, 131 / 90, 72.6, 135, 1 / 87, 70.4, 124 / 94, …
- Course Rating of the tees you play: 71.8
- Slope Rating: 131
- Par: 72
- Handicap allowance: 95%
- **Handicap Index: 12.2**
- **Average of those counted: 12.2125**
- **Differentials counted: Lowest 8 of the most recent 20**
- **Course handicap: 14 strokes**
- **Course handicap before rounding: 13.9434**
- **Playing handicap: 13 strokes**
- Checked against: Python decimal: 20 differentials rounded per Rule 5.1 (89 on 70.4/124 gives 16.95, rounded up to 17.0); lowest 8 average 12.2125 → 12.2; 12.2 × 131/113 − 0.2 = 13.9434 → 14; × 0.95 = 13.25 → 13

### Rules example: three differentials

- Start from: My scores
- Rounds: score, Course Rating, Slope, PCC: 15.3 / 15.2 / 16.6
- Course Rating of the tees you play: 71.8
- Slope Rating: 131
- Par: 72
- Handicap allowance: 95%
- **Handicap Index: 13.2**
- **Rule 5.2a adjustment: -2.0**
- **Differentials counted: Lowest 1 of 3**
- Checked against: Rules of Handicapping 2024, Clarification 5.2a/1: 15.2 − 2 = 13.2

### Rules example: six differentials

- Start from: My scores
- Rounds: score, Course Rating, Slope, PCC: 40.7 / 42.4 / 36.1 / 45.9 / 43.6 / 45.0
- Course Rating of the tees you play: 71.8
- Slope Rating: 131
- Par: 72
- Handicap allowance: 95%
- **Handicap Index: 37.4**
- **Average of those counted: 38.4**
- **Rule 5.2a adjustment: -1.0**
- Checked against: Rules of Handicapping 2024, Clarification 5.2a/2: average of lowest two 38.4 − 1 = 37.4

### Rules example: double rounding, index 8.6

- Start from: My Handicap Index
- Handicap Index: 8.6
- Course Rating of the tees you play: 71
- Slope Rating: 125
- Par: 71
- Handicap allowance: 85%
- **Course handicap before rounding: 9.5133**
- **Course handicap: 10 strokes**
- **Playing handicap: 8 strokes**
- Checked against: Rules of Handicapping 2024, Clarification 6.2a/1: Course Handicap 9.5132…, Playing Handicap (85%) 8

### Rules example: double rounding, index 10.3

- Start from: My Handicap Index
- Handicap Index: 10.3
- Course Rating of the tees you play: 71
- Slope Rating: 125
- Par: 71
- Handicap allowance: 85%
- **Course handicap before rounding: 11.3938**
- **Course handicap: 11 strokes**
- **Playing handicap: 10 strokes**
- Checked against: Rules of Handicapping 2024, Clarification 6.2a/1: Course Handicap 11.3938…, Playing Handicap (85%) 10

### Soft cap with a Low Handicap Index of 8.6

- Start from: My scores
- Rounds: score, Course Rating, Slope, PCC: 88, 71.8, 131 / 92, 70.4, 124 / 85, 71.8, 131 / 90, 72.6, 135, 1 / 87, 70.4, 124 / 94, …
- Low Handicap Index (previous 365 days): 8.6
- Course Rating of the tees you play: 71.8
- Slope Rating: 131
- Par: 72
- Handicap allowance: 95%
- **Index before the soft and hard cap: 12.2**
- **Handicap Index: 11.9**
- Checked against: Rule 5.8 by hand: 12.2 − 8.6 = 3.6; 8.6 + 3.0 + 0.5 × 0.6 = 11.9

## Questions

### How is a golf handicap calculated?

Each round becomes a score differential, (113 ÷ Slope Rating) × (adjusted gross score − Course Rating − PCC). The Handicap Index is the average of the lowest 8 of the most recent 20 differentials, rounded to the nearest tenth (Rules of Handicapping, Rule 5.2b). A score of 88 on a course rated 71.8 with a slope of 131 gives (113 ÷ 131) × 16.2 = 14.0.

### How many rounds do you need for a handicap?

Scores from at least 54 holes, such as three 18-hole rounds (Rule 4.5). With 3 differentials the index is the lowest one minus 2.0; with 4 it is the lowest minus 1.0; with 5 the lowest; with 6 the average of the lowest 2 minus 1.0. The count used then rises to the lowest 8 of 20. The Rules' own example turns differentials of 15.3, 15.2 and 16.6 into an initial index of 13.2.

### What is the difference between Handicap Index and course handicap?

The Handicap Index measures ability on a course of standard difficulty, Slope Rating 113. The course handicap is the number of strokes you get on a particular set of tees: Handicap Index × (Slope ÷ 113) + (Course Rating − par), rounded to a whole number with .5 rounded up (Rule 6.1). A 12.2 index on tees rated 71.8, slope 131, par 72 plays to 14.

### What is the maximum score per hole for handicap purposes?

Net double bogey: par plus 2 plus any handicap strokes you receive on the hole (Rule 3.1b). A player getting one stroke on a par 4 can post no more than 7 there. Until you have a Handicap Index, the limit is par plus 5 (Rule 3.1a). The adjusted gross score is the total after these caps, and it is the figure that goes into the differential.

### What are the soft cap and hard cap?

They limit how fast a Handicap Index can rise (Rule 5.8). If a new index is more than 3.0 above your Low Handicap Index from the previous 365 days, only half of the increase beyond 3.0 counts, and the total rise can never exceed 5.0. With a Low Handicap Index of 8.6 and a calculated 12.2, the soft cap gives 8.6 + 3.0 + 0.3 = 11.9.

### How accurate is the golf handicap calculator?

Accuracy depends on your inputs and the method's assumptions. Decimal arithmetic uses 50 significant digits, but estimates, numerical methods and source data can be less precise; the displayed rounding does not remove those limits. It is checked against 8 worked examples whose answers come from independent sources; for example, “20 rounds on three courses” is checked against Python decimal: 20 differentials rounded per Rule 5.1 (89 on 70.4/124 gives 16.95, rounded up to 17.0); lowest 8 average 12.2125 → 12.2; 12.2 × 131/113 − 0.2 = 13.9434 → 14; × 0.95 = 13.25 → 13.

### Where does the method come from?

USGA and R&A — Rules of Handicapping, effective 2024 (Rules 3.1, 4.5, 5.1–5.3, 5.8, 6.1, 6.2, Appendix C); R&A — Rules of Handicapping, Rule 5: Handicap Index calculation; USGA — What exactly are Course Rating and Slope Rating? (slope 55 to 155, standard 113).

## Sources

- [USGA and R&A — Rules of Handicapping, effective 2024 (Rules 3.1, 4.5, 5.1–5.3, 5.8, 6.1, 6.2, Appendix C)](https://www.usga.org/content/dam/usga/pdf/2024-revision/2024-Rules-of-Handicapping-USGA.pdf)
- [R&A — Rules of Handicapping, Rule 5: Handicap Index calculation](https://www.randa.org/en/roh/the-rules-of-handicapping/rule-5)
- [USGA — What exactly are Course Rating and Slope Rating? (slope 55 to 155, standard 113)](https://www.usga.org/content/usga/home-page/articles/2025/11/what-exactly-are-course-rating-slope-rating.html)