What strokes gained means
Strokes gained measures each shot against what an average golfer would do from the same spot. It turns every shot, from a drive to a two-foot putt, into the same unit: strokes.
Expected strokes
Every position on a golf hole has an expected score: the average number of strokes a golfer takes to hole out from there. A 10 index averages 3.65 from 140 m in the fairway, 3.77 from the same distance in the rough, and 2.02 putts from 6 m.
Those numbers come from millions of recorded shots. They depend on the lie, the distance and the golfer: a Tour player averages 2.96 from that same fairway spot, a scratch player 3.24, a 20 index 4.09.
One shot, one formula
SG = expected(start) − expected(finish) − 1
The shot used one stroke and moved the ball from one expected score to another. If the expected score dropped by more than one stroke, the shot gained; by less, it lost. A holed shot finishes at zero. A penalty stroke costs one more.
A worked hole, scored against a 10 index
| Shot | From | To | Calculation | SG |
|---|---|---|---|---|
| 1 | Tee, 350 m | Rough, 140 m | 4.83 − 3.77 − 1 | +0.06 |
| 2 | Rough, 140 m | Green, 9 m | 3.77 − 2.17 − 1 | +0.60 |
| 3 | Green, 9 m | Green, 1.2 m | 2.17 − 1.31 − 1 | −0.14 |
| 4 | Green, 1.2 m | Holed | 1.31 − 0.00 − 1 | +0.31 |
| Par 4 in 4 | 4.83 − 4 | +0.83 | ||
The drive found the rough, but leaving 140 m on a hole this long is about what a 10 index does. The approach to 9 m was the best shot on the hole. The first putt lost a little: from there a 10 index usually finishes closer than 1.2 m. The shot values always add up to the expected score minus the actual score.
Why the baseline matters
Against the PGA Tour almost every amateur shot loses strokes, which says little about what to practise. Against your own handicap the total sits near zero over enough rounds, and the categories show where your game is stronger or weaker than golfers at your level. Against the next handicap down, they show what it takes to get there.
Shots are grouped the way the PGA Tour does it: off the tee (tee shots on par 4s and 5s), approach (everything else from beyond 27 m, including par-3 tee shots), around the green (within 27 m, off the green) and putting.
Lies
- Tee: the first shot of a hole, read at the hole length. The tee value is the average score on the hole.
- Fairway, rough, sand: distance to the hole in meters or yards (switch between metric and imperial at the top of the page). Sand covers greenside and fairway bunkers.
- Recovery: no normal shot toward the hole, such as behind a tree.
- Green: distance in meters or feet.
Where the numbers come from
The Tour baseline is Mark Broadie's published PGA Tour benchmark (Assessing Golfer Performance on the PGA TOUR, and Every Shot Counts).
The handicap tables for indexes 0 to 20 are one least-squares fit to published Arccos figures, nearly all from Lou Stagner's newsletter, with smaller inputs from MyGolfSpy, Golf Monthly, Shot Scope and Golf Digest. The fit keeps every lie consistent with the others and never lets a higher index beat a lower one. Index 25 is extrapolated. Values between the columns are interpolated, so any index such as 7.4 works.
"Index" is the handicap index as Arccos records it, which can differ from an official World Handicap System index. Putting values are Arccos-based, where putt distance comes from GPS, so short putts look a little harder than in laser-measured data.
How precise
| Tee shots, 300–550 yards | ±0.03 |
| Tee shots under 300 yards | ±0.08 |
| Fairway and rough, 50–250 yards | ±0.05 |
| Inside 50 yards | ±0.10 |
| Greenside sand | ±0.08 |
| Fairway bunkers | ±0.15 |
| Putts of 3–40 feet | ±0.04 |
| Other putts | ±0.08 |
| Recovery | unknown (no amateur data) |
| Index 25 (on top of the above) | add ±0.10 |
Those are uncertainties on each expected-strokes value. Errors are shared between nearby cells, so comparisons between shots and rounds are more reliable than any single number.
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