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Golf Handicap Calculator
Use this free golf handicap calculator to work out your handicap index the World Handicap System way. Enter your most recent rounds — up to 20 — with the score, course rating, and slope rating for each, and the calculator shows every round's differential and your handicap index from the best 8 of your last 20 differentials. You can also enter a single round to see its differential right away.
Your most recent round
Use your adjusted gross score: the score after applying equitable stroke control, with a maximum per hole based on your course handicap. Course rating and slope are printed on the scorecard.
How many differentials count?
| Rounds in your record | Differentials used | Adjustment |
|---|---|---|
| 3 | Lowest 1 | −2.0 |
| 4 | Lowest 1 | −1.0 |
| 5 | Lowest 1 | 0 |
| 6 | Lowest 2 | −1.0 |
| 7–8 | Lowest 2 | 0 |
| 9–10 | Lowest 3 | 0 |
| 11–12 | Lowest 4 | 0 |
| 13–14 | Lowest 5 | 0 |
| 15–16 | Lowest 6 | 0 |
| 17 | Lowest 7 | 0 |
| 18 | Lowest 8 | 0 |
| 19 | Lowest 9 | 0 |
| 20 | Lowest 8 | 0 |
How it works
A golf handicap index is a portable number that describes how good you are, so that players of different abilities can compete fairly. A raw score of 85 means something very different on an easy course than on a hard one, so the World Handicap System, the system now used almost everywhere golf is played, converts every round into a score differential first. The differential adjusts your score for the difficulty of the course you played that day, which makes rounds from different courses directly comparable.
The differential formula is: differential = (adjusted gross score − course rating − PCC) × 113 ÷ slope rating. The course rating is the score a scratch golfer is expected to shoot, so subtracting it measures how many strokes over scratch level you played. The slope rating scales that gap to a course of average difficulty (113 is average; higher means harder for a bogey golfer). The PCC is a small adjustment from −1 to +3 for weather and course setup; on a normal day it is zero.
Before you use a score, it must be an adjusted gross score. That means applying equitable stroke control: a maximum number of strokes per hole, set by your course handicap, so that one blow-up hole does not wreck your whole round or your handicap. If you are not sure of the maximum, most casual golfers use their adjusted score as posted by their club or golf app, which already applies the cap.
Once you have differentials, the handicap index is the average of your best differentials from your most recent 20 rounds, multiplied by 0.96. The number of best differentials used depends on how many rounds you have, as shown in the table above: with 3 rounds only your lowest differential counts, and the count grows until 20 rounds, where the best 8 count. The 0.96 multiplier is called the bonus for excellence — it trims the average slightly to reward good play. Finally, the index is truncated, not rounded, to one decimal place, so an average of 12.29 becomes 12.2, not 12.3.
With fewer than 3 rounds there is no official index, and this calculator says so plainly. With one round, the differential itself is still useful: it tells you exactly how that round compares with your other rounds and with the course. As you add rounds, the index becomes more stable, because a single great or terrible day counts for less. That is the whole point of the best-8-of-20 design — it reflects your demonstrated ability on your good days, not your average day and not your worst day.
Your handicap index is not the same as your course handicap, which is the number of strokes you actually get on a specific course. Course handicap = handicap index × (slope rating ÷ 113) + (course rating − par). A 12.0 index gives a course handicap of about 13 on a slope-125 course and about 11 on a slope-105 course, which is why you should always convert your index for the tees you are playing before a match.
Worked example
A golfer shoots an 85 on a course rated 71.5 with a slope of 125, on a normal day with a PCC of 0.
Step 1: Subtract the course rating from the score — 85 − 71.5 = 13.5.
Step 2: Multiply by 113 — 13.5 × 113 = 1,525.5.
Step 3: Divide by the slope — 1,525.5 ÷ 125 = 12.204, which truncates to a differential of 12.2.
That single round gives a differential of 12.2. It is not yet a handicap index, because one round is not enough — the golfer needs at least two more rounds. If those two rounds produced differentials of 14.6 and 11.8, the three-round index would use the lowest, 11.8, minus 2.0, times 0.96, which is 9.4. Add rounds after that and the best-of count grows as shown in the table, so the index keeps reflecting the best recent play.
FAQ
What is a score differential in golf?
A score differential measures how well you played on a particular course on a particular day, adjusted for how hard that course is. It is calculated as (adjusted gross score minus course rating) times 113 divided by slope rating. A differential of 12.2 from a round of 85 on a course rated 71.5 with a slope of 125 means you played about 12 strokes over the course rating, adjusted for difficulty.
How many scores do I need for a handicap index?
You need at least 3 scores of 18 holes to get an official handicap index. With 3 scores the index uses your lowest differential minus 2.0, with 4 scores it uses the lowest minus 1.0, and with 5 scores it uses the lowest with no adjustment. With 6 scores the index uses the average of your best 2 with a −1.0 adjustment, and from 7 scores on the adjustment drops away while the number of best scores grows until it reaches the best 8 of your most recent 20 scores.
Why is the handicap index multiplied by 0.96?
The 0.96 factor, called the bonus for excellence, slightly rewards players who have shot very good rounds. It means your index is 96 percent of the average of your best differentials, so a player whose best differentials average 12.5 ends up with an index of 12.0. It also keeps the index a touch below your typical best play, which is the point of a handicap.
What is the difference between course rating and slope rating?
Course rating is the score a scratch golfer, a player with a handicap of zero, is expected to shoot on that course from those tees. Slope rating measures how much harder the course plays for a bogey golfer than for a scratch golfer, on a scale where 113 is average and higher numbers mean a bigger gap. Both numbers are printed on the scorecard, and both are needed to turn a raw score into a fair differential.
Can I use this calculator with just one round?
Yes, for an estimate. One round gives you a single differential, which is a useful snapshot of how you played that day, but it is not an official handicap index. An official index needs at least 3 rounds, and it gets more reliable as you add rounds up to 20. Enter your best rounds so far and keep adding new ones as you play.