Golf Handicap Calculator

Enter each round's adjusted gross score with the Course Rating and Slope Rating of the tees you played; both are printed on the scorecard. The adjusted gross score is your score after any hole above net double bogey has been reduced to net double bogey (Rule 3.1), so a blow-up hole counts for less than it did on the card.

In the default example the rounds are 92 (Course Rating 71.2, Slope 128), 89 (70.5, 125), 95 (72.0, 132), 87 (70.5, 125) and 91 (71.8, 130). The 87 works out to (113 ÷ 125) × (87 − 70.5) = 14.916, which rounds to 14.9. The other four round to 18.4, 16.7, 19.7 and 16.7. The calculator shows every differential in the chart so you can see which round is carrying your index.

Because five scores are on file, the Differentials Used row reads 1 of 5 and the adjustment row reads None. The average of the lowest differential is simply 14.9, and the Handicap Index is 14.9.

Then fill in the Target Course fields for where you are about to play. At Slope 128, Course Rating 71.2 and par 71: 14.9 × (128 ÷ 113) + (71.2 − 71) = 16.88 + 0.2 = 17.08, which rounds to a Course Handicap of 17. That is the number of strokes you receive on that course from those tees.

Add a round with the button above the list, and the tool moves to the next row of the table on its own. The list stops at 20 rounds, because only the most recent 20 scores ever count.

Score Differential (Rule 5.1a) = (113 ÷ Slope Rating) × (adjusted gross score − Course Rating − PCC adjustment), rounded to the nearest tenth with .5 rounded up. A negative differential rounds up toward zero, so −1.55 becomes −1.5 (Rule 5.1c). 113 is the Slope Rating of a course of standard difficulty. PCC is set to 0 here.

Handicap Index (Rules 5.2a and 5.2b) = average of the lowest N differentials + adjustment, rounded to the nearest tenth, and never above 54.0 (Rule 5.3). N and the adjustment come from the table for the number of scores on file: 3 scores: lowest 1, −2.0 · 4: lowest 1, −1.0 · 5: lowest 1, no adjustment · 6: average of lowest 2, −1.0 · 7 or 8: lowest 2 · 9 to 11: lowest 3 · 12 to 14: lowest 4 · 15 or 16: lowest 5 · 17 or 18: lowest 6 · 19: lowest 7 · 20: lowest 8 of the most recent 20, no adjustment.

Course Handicap (Rule 6.1a) = Handicap Index × (Slope Rating ÷ 113) + (Course Rating − par), rounded to the nearest whole number.

The tool reproduces the numbered examples in the Rules. Interpretation 5.2a/1 gives three differentials of 15.3, 15.2 and 16.6: the lowest, 15.2, minus 2.0 gives an initial index of 13.2. Interpretation 5.2a/2 gives six differentials of 40.7, 42.4, 36.1, 45.9, 43.6 and 45.0: the average of the lowest two is 38.4, minus 1.0 gives 37.4. Both come out exactly the same in this calculator.

A regular player has 20 scores from the same tees, Course Rating 71.5 and Slope 127: 91, 87, 94, 86, 90, 97, 89, 87, 93, 85, 92, 90, 88, 95, 86, 91, 89, 96, 87 and 90, oldest first. At Slope 127, each stroke above the Course Rating is worth about 0.89 of a differential, so the 85 becomes 12.0, each 86 becomes 12.9 and each 87 becomes 13.8.

With 20 scores the table uses the lowest 8: 12.0, 12.9, 12.9, 13.8, 13.8, 13.8, 14.7 and 15.6. They add up to 109.5, and 109.5 ÷ 8 = 13.6875. Rounded to the nearest tenth, the Handicap Index is 13.7. On a par-72 course at the same ratings, 13.7 × (127 ÷ 113) + (71.5 − 72) = 14.90, a Course Handicap of 15.

Now the player posts an 84, a differential of 11.1. The oldest score, the 91, falls out of the most recent 20. The lowest 8 are now 11.1, 12.0, 12.9, 12.9, 13.8, 13.8, 13.8 and 14.7, averaging 13.125, and the index drops to 13.1. One very good round moved the index by 0.6, because it replaced the 15.6 at the top of the counting eight rather than being averaged across all 20 rounds.

Many older spreadsheets, apps and articles still use the pre-2020 USGA Handicap System. It averaged the best 10 of the last 20 differentials, multiplied by 0.96, a factor called the bonus for excellence, and then truncated the result by dropping every digit after the tenths. The World Handicap System replaced that method in 2020. The best 8 of 20 already gives your good rounds more weight, so the USGA dropped the 0.96 factor. The Rules of Handicapping now say to round to the nearest tenth.

The difference is not cosmetic. Take the 20-round record above. Its average of 13.6875 rounds to 13.7 under the current rules. Put the same average through the retired method and 13.6875 × 0.96 = 13.14, truncated to 13.1, which gives a Course Handicap of 14 instead of 15 on the same course. For the five-round golfer, the old method turns 14.9 into 14.3 and a Course Handicap of 17 into 16. Any tool still applying 0.96 reports every index about 4% too low. That costs a mid-handicap golfer roughly a stroke on a typical course.

Rounding happens twice: once for each Score Differential and once for the final index. If you work out an index by hand, round each differential to one decimal first, then average the ones that count and round again. If you skip the first step, the answer can come out a tenth different from the official one.

This is an educational estimate, not an official Handicap Index. It cannot be used for competitions or posted anywhere, and it will sometimes differ from the index your golf club or GHIN shows. It leaves out several parts of the Rules of Handicapping. The Playing Conditions Calculation (Rule 5.6) compares scores from the whole field each day and can change differentials by −1.0 to +3.0. It needs at least eight acceptable scores from that day, so this tool sets it to 0.

The soft cap and hard cap (Rule 5.8) are not modelled. Once you have 20 scores, your Low Handicap Index is the lowest index you held in the past 365 days. If a new index is more than 3.0 strokes above it, only 50% of the increase beyond 3.0 counts. The hard cap then stops the index from rising more than 5.0 strokes above it. The tool has no dated history to check against, so after a bad run its index can be higher than your official one. The exceptional score reduction (Rule 5.9) is also left out. A differential 7.0 to 9.9 strokes below your current index cuts 1.0 from it, and 10.0 or more cuts 2.0, so after a career round the official index can be lower than the tool's.

The tool also expects 18-hole scores that have already been adjusted to net double bogey. It does not scale up 9-hole scores or apply Committee adjustments.

Other sports handle handicaps and ratings differently. The Bowling Handicap Calculator uses a flat percentage of the gap between your average and a league basis score. It drops the fractional pin, a truncation step golf no longer uses. The Darts Checkout Calculator works on a different kind of scoring problem: finding a legal three-dart finish for whatever score is left. The Board Game Elo Rating Calculator is a rating system that moves after every result depending on who you beat, where a golf index averages your best recent rounds. To check the rounding step by hand, the Rounding Calculator rounds to the nearest tenth using half-up, the mode the Rules of Handicapping use. Its floor mode gives the same result as the old truncation for a positive number. Understanding Calculator Formulas explains how to check any formula on this site against its worked example.