⛳ Golf Handicap Index Calculator
Add your recent rounds — score, course rating, and slope for each — to estimate your handicap index, with the score differentials and how many of them count toward the result.
🧮 Estimate Your Index
What is a Handicap Index?
A handicap index is a portable measure of your demonstrated ability, letting golfers of different standards compete fairly. It is built from the best of your recent score differentials — each round normalised for how hard the course and tees played — rather than a simple scoring average, so a few great rounds carry more weight than your bad days.
Enter three to twenty rounds and this calculator sorts the differentials, averages the lowest few (8 of your last 20 once you have them), applies the small-sample adjustment, and rounds to one decimal place. Treat the number as a well-grounded estimate for planning matches and tracking progress, not an official issued index.
❓ Frequently Asked Questions
How is a handicap index calculated?
Each round is turned into a score differential — (adjusted gross score − course rating) × 113 ÷ slope. Your differentials are sorted, and the lowest few are averaged depending on how many rounds you've entered. With 20 rounds the best 8 count; with fewer, a smaller set is used along with a small adjustment. The average, rounded to one decimal and capped at 54.0, is your handicap index.
How many rounds do I need?
You need at least three. This tool accepts 3 to 20 rounds. With only a handful of scores an adjustment is applied and fewer differentials count, so the index firms up as you post more rounds — with 20 on record, the lowest 8 differentials are averaged.
What are course rating and slope?
Course rating is the score a scratch golfer is expected to shoot from a set of tees, and slope (55–155, with 113 as standard) reflects how much harder the course plays for a bogey golfer. Both are printed on the scorecard and are specific to the tees you played.
Is this an official handicap?
No. It's an estimate for practice and planning that mirrors the World Handicap System maths. An official index must be issued by an authorised golf association from scores posted at rated courses.