How the WHS Handicap Calculation Works
The World Handicap System (WHS) was rolled out globally in 2020 and is now the single standard used by R&A, USGA and national federations including England Golf. It uses a simple idea: rate each round against the difficulty of the course you played, then average your best recent results.
Step 1 — Score Differential
Every round gets a Score Differential:
Differential = (Adjusted Gross Score − Course Rating) × 113 ÷ Slope Rating113 is the slope of a course of standard difficulty. A higher slope (harder course for the bogey golfer) lowers the differential — i.e. you get credit for playing a tougher course.
Step 2 — Best differentials
Your Handicap Index is the average of your best differentials from your most recent 20 rounds. With fewer rounds, the WHS uses a smaller set:
- 3 rounds → best 1 (minus 2.0 adjustment)
- 4 rounds → best 1 (minus 1.0)
- 5 rounds → best 1
- 6 rounds → best 2 (minus 1.0)
- 7–8 rounds → best 2
- 9–11 rounds → best 3
- 12–14 rounds → best 4
- 15–16 rounds → best 5
- 17–18 rounds → best 6
- 19 rounds → best 7
- 20 rounds → best 8
9-hole rounds
A 9-hole score is scaled up to an 18-hole equivalent by doubling the score and adding 1 stroke before calculating the differential against the full 18-hole rating.
Frequently asked questions
Where do I find course rating and slope?
They're printed on the official scorecard for each set of tees, or you can find them on your national federation's course rating database (e.g. England Golf, USGA GHIN).
Why is my handicap different to my club's?
This tool gives you a true WHS calculation from the rounds you enter. Your club handicap may include additional rounds you haven't entered here, or apply soft/hard caps from previous indexes.
What is "Adjusted Gross Score"?
Under the WHS, the maximum you can score on any hole for handicap purposes is net double bogey (par + 2 + any handicap strokes you receive on that hole). For most weekend rounds this only affects disaster holes.