World Handicap System index from your recent scores, course ratings, and slopes — per-round differentials, best-of counting, and the formula shown.
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FORMULA USEDGolf Handicap Calculator
What a handicap is for
A handicap index exists so golfers of different ability can compete fairly: it estimates the number of strokes above (or below) scratch you would score on a course of standard difficulty. Under the World Handicap System (WHS, adopted worldwide in 2020), the index comes from your recent scores adjusted for how hard each course actually played.
Differentials, then the index
Each round first becomes a score differential: (score − course rating) × (113 ÷ slope). Course rating is the scratch score for the tee; slope measures relative difficulty for a bogey golfer, with 113 as standard. The index is then the average of your best 8 differentials from your last 20 rounds — with fewer rounds on file, fewer differentials are used (best 2 of 5, for example), and 3 scores is the minimum to hold an index at all. The maximum WHS index is 54.0.
Course rating vs. slope rating
They answer different questions. Course rating (around 67–77) is the expected score of a scratch golfer on that tee. Slope (55–155, with 113 standard) measures how much harder the tee plays for a bogey golfer than a scratch golfer — water, forced carries, and long rough push slope up because they punish the higher handicapper disproportionately. An 88 shot on a 74.5/140 mountain course is a better round than an 88 on a 70.5/115 muni, and the differential formula prices that correctly.
Worked example
Five rounds entered; round 1: an 88 on a course rated 71.8 with slope 125.
All five differentials: 17.6, 15.5, 19.5, 16.7, 14.6 → best 2 of 5 are 14.6 and 15.5.
Index = (14.6 + 15.5) ÷ 2 = 15.1.
How to use it
List your recent scores comma-separated, oldest first, up to 20.
Enter each round’s course rating and slope rating from the scorecard, aligned one-to-one.
Check the per-round differentials in the table — they are the raw material.
Read your WHS index and how many of your best differentials it used.
Frequently asked questions
What is a golf handicap?
A number, accurate to one decimal, that estimates how many strokes over (or under) scratch you shoot on a standard-difficulty course. It lets a 15-index and a 5-index have a fair match: the higher player receives the difference as extra strokes, allocated by the hole difficulty ranking on the card.
How many scores do I need to calculate a handicap?
Three acceptable scores is the WHS minimum, which establishes an index from the single lowest differential. From 9–11 scores the best 3 are used, and once you have 20 on file the index is the average of your best 8. This calculator follows that same sliding scale.
What is a course rating and slope rating?
Course rating is the score a scratch golfer is expected to shoot from a tee; slope (55–155, with 113 standard) measures how much harder that tee is for a bogey golfer than for a scratch golfer. The pair re-price every score: shooting your average on a high-slope, high-rating course earns a lower differential than the same number on an easy track.
What does my handicap number mean?
Roughly, your expected strokes over par on a standard course: a 15.1 index plans to shoot about 87 on a par-72 course of standard difficulty. On a specific course you receive a course handicap — your index scaled by that tee’s slope, shown on the board for a 130-slope example.
Can I have a negative handicap?
Yes — plus handicaps. Scores consistently below the course rating produce negative differentials, and their average is written with a plus sign, as in +1.4. Elite amateurs and tour players live there; the calculator formats it the same way.
How often should I update my handicap?
Post every acceptable round the day you play it, and the index recomputes automatically — daily revision is the WHS norm. Because only your best 8 of the last 20 count, one bad round barely moves the number, while a great round can drop it immediately.