What this calculator does
Turn your recent golf scores into an estimate of your Handicap Index, the number that shows how well you play. A handicap measures the ability you've shown, so players of different skill can compete fairly. Golf associations around the world use the World Handicap System. Under it, every round becomes a score differential. That's how many strokes over the Course Rating you shot, adjusted to a course of standard difficulty using the Slope Rating. Your Handicap Index is then the average of your best recent differentials.
This calculator uses those published formulas. Enter one round to get its score differential. Or list your recent scores with their Course and Slope Ratings to get a Handicap Index. The result is an unofficial estimate. Only an authorized golf association or club can issue an official Handicap Index. They also apply safeguards this calculator doesn't model.
Where it's used
Why this math matters outside the classroom:
- Weekend golf. A golfer who shoots 85 on tees rated 71.2 with a slope of 128 gets a differential of 113 ÷ 128 × 13.8 ≈ 12.2.
- Club competitions. Organizers compare players' Handicap Indexes so that a 5.0 and a 20.0 can compete in the same net event.
- Tracking improvement. A player whose lowest 8 of 20 differentials fall from an average of 18.4 to 15.2 sees the index drop by 3.2.
- Statistics class. Students average the lowest values in a data set and discuss why a best-rounds mean differs from the overall mean.
Grade level and standards: Grades 6–7; Common Core State Standards for Mathematics 6.SP.B.5.c, 7.NS.A.3. © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved.
How to use it
- Choose whether you want the differential for one round or a Handicap Index from several rounds.
- For one round, enter your adjusted gross score and the Course Rating and Slope Rating of the tees you played. Add the playing conditions adjustment too (usually 0).
- For a Handicap Index, list 3 to 20 recent 18-hole scores, oldest first. Add one Course Rating and Slope Rating for all of them, or one per round.
- Read the Handicap Index. Then check the table to see which differentials were counted.
What the inputs mean
- Adjusted gross score
- Your score after limiting any hole to net double bogey. That's double bogey plus any handicap strokes you get on that hole. Golf association apps make this adjustment when you post a score.
- Course Rating
- The Course Rating is the score a scratch golfer (one who plays to a handicap of zero) is expected to shoot from those tees, such as 71.2. It's printed on the scorecard.
- Slope Rating
- The Slope Rating shows how much harder the course plays for a bogey golfer than for a scratch golfer, from 55 to 155. A course of standard difficulty is 113.
- Playing conditions adjustment (PCC)
- The playing conditions calculation adjusts for days when weather or course setup made scoring unusually hard or easy. It ranges from −1 to +3 and is 0 on most days.
- Adjusted gross scores, oldest first
- List scores from oldest to newest. Only the most recent 20 count, and you need at least 3.
- Course Ratings (one, or one per score)
- One value is used for every round; otherwise list one per score in the same order.
Formula and method
score differential = (113 ÷ Slope Rating) × (adjusted gross score − Course Rating − PCC) Handicap Index = average of the lowest 8 of the most recent 20 differentials fewer than 20 scores: 3 → lowest 1 − 2.0; 4 → lowest 1 − 1.0; 5 → lowest 1; 6 → lowest 2 − 1.0; 7–8 → lowest 2 9–11 → lowest 3; 12–14 → lowest 4; 15–16 → lowest 5; 17–18 → lowest 6; 19 → lowest 7 differentials and the index are rounded to the nearest tenth; the maximum index is 54.0
PCC is the playing conditions adjustment. The adjusted gross score is your score after the net double bogey limit. Subtracting the Course Rating shows how far above a scratch golfer's expected score you played. Multiplying by 113 ÷ Slope Rating rescales that to a course of standard difficulty. That way a round on a hard course and a round on an easy course can be compared.
Averaging only your best differentials makes the Handicap Index reflect what you can do, not your typical round. With only a few scores on record, the rules average fewer differentials. For the shortest records, they also subtract a small adjustment. That keeps new players from starting with an index that's too high.
Worked example
You have posted 10 rounds, all from tees with a Course Rating of 71.2 and a Slope Rating of 128: 90, 88, 95, 86, 92, 89, 91, 87, 93 and 85.
- Most recent round: (113 ÷ 128) × (85 − 71.2) = 12.18, which rounds to 12.2.
- The ten differentials are 16.6, 14.8, 21.0, 13.1, 18.4, 15.7, 17.5, 13.9, 19.2 and 12.2.
- With 10 scores the rules use the lowest 3: 12.2, 13.1 and 13.9.
- Average: (12.2 + 13.1 + 13.9) ÷ 3 = 13.0667, which rounds to 13.1.
Result: Your unofficial Handicap Index would be 13.1. A single round of 90 on these tees has a score differential of 16.6.
Understanding the result
A Handicap Index describes your ability on a course of standard difficulty. Before a round, it's turned into a Course Handicap for the tees you play. That's the number of strokes you receive, and a harder course gives more strokes.
Because the index averages your best rounds, your typical score will usually be a few strokes worse than the index suggests. That's on purpose. The system measures what you can do on a good day.
Assumptions and limitations
- Each score is an 18-hole adjusted gross score, already limited to net double bogey on each hole.
- In the Handicap Index mode, the playing conditions adjustment is 0 for every round.
- Ratings are those of the tees you actually played.
- Unofficial: only an authorized golf association or club can issue a Handicap Index.
- Some rules aren't modelled. These include the soft and hard caps, which limit how fast an index can rise above your lowest index of the past year. They also include cuts for exceptional scores and the handling of 9-hole scores.
- Exact halves are rounded up (round half up). Your association's software is the final word on any borderline value.
Frequently asked questions
What is a good Handicap Index?
Lower is better. 0 is a scratch golfer, and a plus index (shown as a negative number here) is better than scratch. The maximum is 54.0. There's no single good number. An index just describes how you play right now. It's most useful for tracking your own progress and for fair matches.
Why 113?
113 is the Slope Rating of a course of standard difficulty. Multiplying by 113 ÷ Slope Rating turns a score from any course into what it would be on that standard course. That's how rounds from different courses can be averaged together.
How many rounds do I need?
Three 18-hole scores are enough for a first Handicap Index under the World Handicap System. With fewer than 20 scores, fewer differentials are averaged. Records of 3, 4 or 6 scores also get a small downward adjustment.
Is this my official handicap?
No. It uses the published formulas, but an authorized golf association works out and issues the official Handicap Index. The association also applies caps and other safeguards. Use this to understand or check how the number is built.
How this calculator is checked
Method: World Handicap System, Rules of Handicapping (USGA and R&A): Rule 5.1 score differential (113 ÷ Slope Rating × (adjusted gross score − Course Rating − PCC)) and Rule 5.2 Handicap Index (lowest 8 of 20; Rule 5.2a table for fewer than 20 scores), checked 2026-10-19. The calculation is covered by automated tests with known reference values and edge cases. Last updated 2026-10-18. Found a problem? Tell us.
Embed this calculator
Put this Golf Handicap Calculator on your own website or blog for free. Paste this code where you want it to appear: