What a Handicap Does
A handicap lets golfers of different abilities compete fairly. It is an estimate of your demonstrated potential — not your average score, but roughly what you shoot on a good day.
Since 2020 most of the world has used the World Handicap System, which unified six previously separate national systems into one set of rules.
The Score Differential
Every round is converted into a differential that removes the effect of course difficulty, so rounds on different courses can be compared directly.
Score differential = (113 ÷ Slope rating) × (Adjusted gross score − Course rating)
The number 113 is the slope rating of a course of average difficulty, and it appears throughout the system as the reference point.
Course Rating and Slope
| Measure | What it means | Typical range |
|---|---|---|
| Course rating | The score a scratch golfer is expected to shoot | 67–77 |
| Slope rating | How much harder the course plays for a bogey golfer than a scratch one | 55–155, average 113 |
The two are independent. A long, open course may have a high rating and a low slope — hard for everyone, but not disproportionately hard for weaker players. A short course with forced carries over water has the opposite profile.
How the Index Is Calculated
The system takes the best differentials from your most recent 20 rounds. With fewer rounds it uses a smaller sample and applies an adjustment:
| Rounds submitted | Differentials used | Adjustment |
|---|---|---|
| 3 | Lowest 1 | −2.0 |
| 4 | Lowest 1 | −1.0 |
| 5 | Lowest 1 | 0 |
| 6 | Lowest 2 | −1.0 |
| 7–8 | Lowest 2 | 0 |
| 9–11 | Lowest 3 | 0 |
| 12–14 | Lowest 4 | 0 |
| 15–16 | Lowest 5 | 0 |
| 17–18 | Lowest 6 | 0 |
| 19 | Lowest 7 | 0 |
| 20 | Lowest 8 | 0 |
Using the best 8 of 20 is the key design choice. It means your index reflects what you are capable of, not what you typically do — which is why most golfers shoot above their handicap most of the time.
From Index to Strokes
Course handicap = Index × (Slope ÷ 113) + (Course rating − Par)
The index is portable; the course handicap is what you actually receive on a given set of tees. A 12.0 index becomes 13 strokes on a slope-125 course and 11 on a slope-105 one.
Playing handicap applies a further allowance set by the competition format — commonly 95% in individual stroke play, and lower in four-ball formats.
Net Double Bogey
The system caps the score you may post on any single hole at net double bogey: par + 2 + any handicap strokes you receive on that hole. A disastrous hole therefore cannot distort your index, which is what makes the system robust against one bad swing.
Handicap Ranges
| Index | Standard | Typical 18-hole score |
|---|---|---|
| +2 to 0 | Scratch or better | 70–72 |
| 1–5 | Very good | 73–78 |
| 6–12 | Good club golfer | 79–85 |
| 13–20 | Average club golfer | 86–95 |
| 21–28 | Improving | 96–105 |
| 29–54 | Beginner | 106+ |
The maximum index is 54.0 for all players. A "plus" handicap such as +2.4 means the player gives strokes rather than receiving them.
Other Features of the System
- Playing conditions calculation. If scores across a course on a given day are unusually high or low, differentials are adjusted for weather and course setup.
- Soft and hard caps. An index cannot rise more than 3.0 above its lowest value in the past year without being restrained, preventing gradual inflation.
- Exceptional score reduction. A round 7 or more strokes better than your index triggers an immediate downward adjustment.
- Daily updates. Indexes recalculate overnight rather than twice a month as under older systems.
Frequently Asked Questions
How many rounds do I need?
Three 18-hole rounds produce an initial index, though it will move considerably until you have posted 20.
Why is my average score higher than my handicap?
Because the index measures potential, not average. Using the best 8 of 20 means a typical golfer shoots about 3 strokes above their course handicap on a normal day.
Can I combine 9-hole rounds?
Yes. Two 9-hole scores combine into an 18-hole differential, and a 9-hole round on its own produces a 9-hole differential the system can use.
Is this an official handicap?
No. An official index must be issued by an authorised golf association from scores posted at rated courses with peer review. This calculator applies the same formulas for your own reference.