The formula to calculate Handicap Index is:

\[ \text{Handicap Index} = \frac{\sum \text{Best Differentials}}{\text{Number of Differentials}} \]

Where:

- Best Differentials are the lowest score differentials from your scores.
- Number of Differentials is typically 8 out of 20 scores.

The Handicap Index is a measure of a golfer's potential ability on a course of standard playing difficulty.

Course Rating is the evaluation of the playing difficulty of a course for a scratch golfer under normal course and weather conditions.

Slope Rating is the evaluation of the relative playing difficulty of a course for a bogey golfer compared to a scratch golfer.

Let's assume the following values:

- Scores: 85, 87, 90, 88, 86, 84, 89, 91, 92, 88, 87, 85, 86, 90, 89, 88, 87, 85, 84, 83
- Course Rating: 72.0
- Slope Rating: 113

Using the formula:

\[ \text{Handicap Index} = \frac{\sum \text{Best Differentials}}{\text{Number of Differentials}} \]

Evaluating:

The Handicap Index is calculated based on the best 8 differentials from the 20 scores.

Scores | Course Rating | Slope Rating | Handicap Index |
---|---|---|---|

85, 87, 90, 88, 86, 84, 89, 91, 92, 88, 87, 85, 86, 90, 89, 88, 87, 85 | 72 | 113 | 13.63 |