Chasing Pure
How the Ranking Works
You post a score. We turn it into a world rank — your place among roughly 70 million golfers. No hand-waving: here is every step of the math, exactly as the engine runs it.
Step 1 · We measure how hard the course was
Not all 95s are equal. A 95 at your local muni is a different round than a 95 at Bandon Dunes from the back tees. Every rated course carries two numbers for each set of tees:
- Course Rating — what a scratch golfer is expected to shoot. Bandon Dunes back tees: 75.8.
- Slope — how much harder the course plays for a bogey golfer relative to a scratch golfer. Average slope is 113; Bandon Dunes back is 144.
Pick your course and tee and we pull both numbers in automatically.
Step 2 · Your round becomes a Differential
One formula turns your score and the course’s difficulty into a single comparable number — the World Handicap System’s Score Differential:
Differential = (Your Score − Course Rating) × (113 ÷ Slope)
Worked, for a 95 at Bandon back:
(95 − 75.8) × (113 ÷ 144) = 15.07
The 113 is the average slope — it normalizes every course to one scale, so a differential means the same thing everywhere.
If you post nine holes
WHS lets you turn in a nine and completes the round with an expected nine based on your current index:
Expected nine = (0.5 × your index) + 1.5
Your round’s differential is the nine you played (same formula, using the nine-hole rating and slope) plus that expected nine:
Differential = (your played nine) + (expected nine)
First round ever, before you have an index? The unplayed nine is assumed to mirror the one you played — so the differential is simply 2 × your played nine.
Step 3 · Your Differentials become your Handicap Index
This is the official World Handicap System (WHS 2024) method — not a Chasing Pure shortcut. Your index is the average of your best differentials from your last 20rounds. How many count as “best,” and whether a small adjustment applies, depends on how many rounds you’ve posted. This is WHS Table 5.2a, exactly:
| Rounds in your last 20 | Best differentials averaged | Adjustment |
|---|---|---|
| 1 – 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 – 11 | lowest 3 | 0 |
| 12 – 14 | lowest 4 | 0 |
| 15 – 16 | lowest 5 | 0 |
| 17 – 18 | lowest 6 | 0 |
| 19 | lowest 7 | 0 |
| 20+ | lowest 8 | 0 |
So your index sharpens as you play. Chasing Pure names the stages: Provisional standing (1–4 rounds), Provisional index (5–19 rounds), and Your index (20+).
Worked, for your very first round — one differential of 15.07, so “lowest 1” with a −2.0 adjustment:
15.07 − 2.0 = 13.07
That −2.0 isn’t us being cautious — it’s the official WHS adjustment for a record this short. Finally, the index is held to the WHS range: floor −10, ceiling 54.
Step 4 · Your Index becomes your World Rank
Now we place your index on the whole golfing population. We model roughly 70 million golfers, using the USGA’s handicap-range data as the shape of that population. Each band holds a share of all golfers:
| Index range | Share of golfers | This good or better |
|---|---|---|
| 0 and better (down to −10) | 0.34% | 0.34% |
| 0 – 5 | 1.51% | 1.85% |
| 5 – 10 | 4.74% | 6.59% |
| 10 – 15 | 8.58% | 15.17% |
| 15 – 20 | 13.76% | 28.92% |
| 20 – 25 | 18.27% | 47.20% |
| 25 – 30 | 19.03% | 66.22% |
| 30 – 35 | 15.56% | 81.78% |
| 35 – 40 | 9.84% | 91.61% |
| 40 – 45 | 4.75% | 96.36% |
| 45 – 50 | 2.10% | 98.46% |
| 50 – 54 | 1.54% | 100.00% |
“This good or better” is the running share of all golfers whose index is at or below the top of each band.
Below scratch, the field thins fast — each stroke better than scratch is about twice as rare as the last. A scratch golfer sits near #240,000; a +5 lands around #7,500; and the roughly 900 best golfers in the world reach the #1,001 ceiling. A single-digit handicap is genuinely elite here, and a plus handicap is rare air.
To rank you, we read where your index falls. For an index inside a band, we interpolate straight-line between the band’s lower and upper cumulative shares. Worked, for your index of 13.07 (the 10–15 band):
everyone under index 10 → 6.59% are already ahead
within the 10–15 band: (13.07 − 10) ÷ (15 − 10) = 61.4% of the way up
61.4% × 8.58% = 5.27% more
6.59% + 5.27% = 11.86% are as good or better → 88.14% rank behind you
Your rank is that share of the 70 million:
11.86% × 70,000,000 ≈ #8,298,900
— with roughly 61.7 million golfers ranked behind you off a single round.
The ceiling: #1,001
Chasing Pure caps the very top at #1,001 — one behind the OWGR’s top ~1,000 ranked professionals. If your index is elite enough that the raw math would place you inside that top 1,000, we show #1,001 and “you’ve mastered this level” instead of a number. It’s a deliberate horizon: the officially-ranked pros sit above it. That’s the next thing to chase.
We compute at full precision and round these figures for reading, so your rank can differ by a hair from a hand-calc with the rounded numbers. And these band shares are Chasing Pure’s current population model — if we recalibrate the curve, this table updates with it.