WHS Handicap Index calculator
Enter the adjusted gross score, Course Rating and Slope Rating of each round. The calculator returns a Score Differential per round, then your Handicap Index: the average of your lowest differentials, using the number of scores Rule 5.2a sets for the size of your record.
| Round | Adjusted gross score | Course Rating | Slope Rating | Differential |
|---|---|---|---|---|
| 1 | — | |||
| 2 | — | |||
| 3 | — |
How to use this calculator
- Enter each round
For every round, enter the adjusted gross score you shot, plus the Course Rating and Slope Rating of the tees you played. Both are printed on the scorecard.
- Read the differential per round
The tool converts each round into a Score Differential, which is that score expressed on a course of standard difficulty. Rows counted towards your Index are highlighted.
- Read your Handicap Index
Your Index is the average of the lowest differentials, over the number of scores Rule 5.2a retains for the size of your record, plus any adjustment that applies.
The official formula
Every round becomes a Score Differential, which is the score you shot expressed on a standard course. That is what makes a 92 at a hard course comparable to an 86 at an easy one.
Score Differential = (113 ÷ Slope Rating) × (adjusted gross score − Course Rating − PCC adjustment)
113 is the Slope Rating of a course of standard difficulty, so the first bracket is simply how much harder or easier your course is than standard. The PCC adjustment accounts for abnormal playing conditions on the day; it runs from −1.0 to +3.0 and is 0 on most days, which is what this calculator assumes.
Handicap Index = average of the lowest Score Differentials in your record + adjustment
How many rounds count
A full record is the lowest 8 of your last 20. Below 20 rounds, fewer differentials count and a short record is adjusted downwards, because a small sample flatters a player.
| Differentials in record | Used in the calculation | Adjustment |
|---|---|---|
| 3 | Lowest 1 | -2.0 |
| 4 | Lowest 1 | -1.0 |
| 5 | Lowest 1 | 0 |
| 6 | Average of lowest 2 | -1.0 |
| 7-8 | Average of lowest 2 | 0 |
| 9-11 | Average of lowest 3 | 0 |
| 12-14 | Average of lowest 4 | 0 |
| 15-16 | Average of lowest 5 | 0 |
| 17-18 | Average of lowest 6 | 0 |
| 19 | Average of lowest 7 | 0 |
| 20 | Average of lowest 8 | 0 |
Source: Rules of Handicapping, Rule 5.2a (USGA / R&A, 2024 revision). Three rounds is the minimum for an initial Handicap Index, and the maximum is 54.0.
Why a Slope Rating outside 55–155 is rejected
The Slope Rating scale is defined on 55 to 155, where 113 is standard. A value outside it is not an unusually hard or easy course, it is a bad record — and they exist: of the 5,929 live tee sets we hold for French courses, 79 sit outside the legal range, some as low as 32. The calculator refuses them rather than returning a wrong Index with a straight face.
Frequently asked questions
How is a WHS Handicap Index calculated?
Each acceptable round is converted into a Score Differential with the formula (113 ÷ Slope Rating) × (adjusted gross score − Course Rating − PCC adjustment), rounded to one decimal. Your Handicap Index is then the average of the lowest differentials in your record — the lowest 8 of the last 20 once the record is full — rounded to one decimal.
How many rounds do you need for a handicap index?
Three. With exactly three, only your lowest differential counts and 2.0 is subtracted from it; with four, 1.0 is subtracted. Those adjustments exist because three rounds flatter a player, and they disappear from five rounds onwards as the record grows.
What is a Score Differential in golf?
It is your score for one round expressed on a course of standard difficulty, so that rounds played on different courses and different tees can be compared and averaged. It is the unit a Handicap Index is built from — an Index is never an average of your scores, it is an average of your differentials.
What is the PCC adjustment?
The Playing Conditions Calculation compares how a field actually scored on a given day against how it was expected to score, and shifts every differential from that day between −1.0 and +3.0. It is computed automatically by your federation once enough scores are in, so it is 0 for a round you are calculating by hand.
Is my Handicap Index the number of strokes I get?
No. The Handicap Index is portable and course-independent; the strokes you actually receive are your Course Handicap, which is the Index × (Slope Rating ÷ 113) + (Course Rating − par), rounded to a whole number. The same Index gives you a different number of strokes at every course and from every set of tees.