Build log
The benchmarks behind Round X-Ray
Round X-Ray takes the six stats from a single round and turns them into an estimate of where the strokes went: off the tee, approach play, short game, putting, or penalties. This post is the arithmetic behind it, written out in full, because a number without its method attached isn't worth much.
What it isn't
It isn't the PGA Tour's strokes-gained statistic. Real strokes gained is built from ShotLink data: the exact distance and lie of every shot, compared against a huge database of outcomes from that same distance and lie. Nobody tracking their own round with a pencil has access to that. What follows is a simplified, rule-of-thumb model built for one purpose: pointing a bogey golfer toward the practice area most likely to matter, not producing a tour-grade statistic.
The benchmarks
Three benchmark groups, each an approximate midpoint drawn from commonly published amateur golf statistics rather than a single proprietary dataset:
| Group | Fairways hit | GIR | Putts | Up-and-down |
|---|---|---|---|---|
| Bogey golfer (~20 to 24 hcp) | 40% | 20% | 34 | 15% |
| Mid handicap (~10 to 15 hcp) | 50% | 33% | 32 | 25% |
| Single digit (~0 to 9 hcp) | 58% | 50% | 30 | 40% |
Turning a percentage gap into strokes
The harder problem is converting "you hit 10 percentage points fewer fairways than the benchmark" into an actual number of strokes. There's no exact conversion without shot-level data, so the calculator uses weights that follow the shape of the strokes-gained research discussed in the previous post: approach play and short game are weighted more heavily than driving, because that's where the published gap between skill levels is largest.
- Off the tee: 0.4 strokes for every percentage point below the benchmark fairway rate, across your driving holes.
- Approach: 0.7 strokes for every percentage point below the benchmark GIR rate, across all 18 greens.
- Short game: 0.9 strokes for every percentage point below the benchmark up-and-down rate, applied only to the greens you missed.
- Putting: 1 stroke for every putt above the benchmark total. This one's exact, a putt is a putt.
- Penalties: counted directly, 1 stroke per penalty stroke taken. Also exact.
Add the five categories together and you get an estimate of total strokes to gain, alongside a ranked list of which category is the biggest opportunity for that specific round.
Where it's weakest
Being upfront about the limits: a single round is a small sample, one bad three-putt hole can swing the putting number more than it should. The weights are a considered simplification, not a regression fit to your own data. And "up-and-down rate" from one round can be based on very few attempts. The tool is built to point you in a direction worth practising, not to hand down a verdict. If you log a handful of rounds and the same category keeps showing up as the leak, that's a far more reliable signal than any single result.
The full source for the calculator is plain JavaScript, no server, nothing sent anywhere. If you want to see exactly how an input turns into an output, view the page source, it's meant to be read.