Reference
How your handicap is calculated
Your index here is unofficial, built the way the World Handicap System builds one. Here's every step.
What the number means
A Handicap Index isn't your average score. It's what you shoot when you play well, so it uses your best recent rounds and throws the rest away. Lower is better.
0.0 is scratch. Above it you get strokes, so a 12.4 index gets about twelve. Below it you give strokes back, and the number is written with a plus (+2.4). A plus in front of your index means you're better than scratch, not worse.
Step 1 · Every round becomes a Score Differential
A round of 82 means nothing on its own. It depends on the course and the tee. So every round becomes a Score Differential first: how you played, on a scale that reads the same everywhere.
- Course Rating
- What a scratch golfer is expected to shoot from that tee. It's usually lower than par, which is why an even par round can come out near zero. Par isn't in the formula at all.
- Slope
- How much harder the course plays for a bogey golfer than for a scratch golfer, from 55 to 155. Dividing by it puts every course on one scale. 113 is the standard.
- Gross
- Your total strokes, as written on the card. We don't cap a hole that got away from you. An 11 counts as an 11.
A nine uses its own rating and slope, and we double the result so it can sit beside full rounds. Rating and slope come off your card or the course lookup. A round saved without them keeps its score and stats, but it has no differential, so it can't feed the index.
Step 2 · We average your best differentials
With a full record, your index is the average of your best 8 of the last 20 rounds. Only the last 20 count, so old rounds drop off as you play.
Before you have 20, the WHS uses a smaller table, with an adjustment. Under 3 rounds there's no index at all.
| Rounds you have | Lowest we average | Adjustment |
|---|---|---|
| 3 | 1 | −2.0 |
| 4 | 1 | −1.0 |
| 5 | 1 | none |
| 6 | 2 | −1.0 |
| 7 to 8 | 2 | none |
| 9 to 11 | 3 | none |
| 12 to 14 | 4 | none |
| 15 to 16 | 5 | none |
| 17 to 18 | 6 | none |
| 19 | 7 | none |
| 20 | 8 | none |
The adjustment only ever makes your index lower. A few cards haven't shown what you can shoot yet, and the system would rather give you an index that's too strong than let a thin record earn an easy one. It halves at four rounds, clears at five, comes back once at six, and is gone from seven on.
Step 3 · Round down and cap
The result is truncated to one decimal, not rounded, so 12.39 becomes 12.3. It's capped at 54.0. A negative result is a plus handicap, and shows with a leading plus.
A worked example
Three rounds, none of them under par. Here's every number the app takes from them.
| Round | Gross | To par | Rating | Slope | Differential |
|---|---|---|---|---|---|
| Home course | 74 | +3 | 70.3 | 113 | 3.7 |
| Nine after work9 holes | 31 | +1 | 30.5 | 108 | 1.0 |
| The muni | 72 | E | 71.5 | 124 | 0.5 |
- Three rounds, so the table says average the lowest 1, then apply −2.0.
- The lowest is 0.5, the even par 72. It sat 0.5 strokes above that course's rating. The other two rounds are dropped.
- 0.5 − 2.0 = −1.5. That's below scratch, so it shows as +1.5.
So three rounds over par produced a +1.5 index. The 72 was a scratch round once the rating is counted, and with only three cards the table takes another 2.0 off.
It settles quickly. A fourth round halves the adjustment, a fifth clears it, and by seven your index averages two rounds instead of leaning on one. The line under your index says how many are feeding it. “Best 1 of 3” means one card is doing all the work.
What this is not
This index is unofficial. It follows the WHS method, but no golf association issued it, so don't enter it where an official index is required. That takes a club and your national association.
Four parts of the full WHS aren't applied here:
- Net Double Bogey. The official method caps each hole. We use your gross as written.
- Playing Conditions Calculation. No adjustment for a day the whole field struggled.
- Soft and hard caps. No brake on how fast your index can climb away from its recent low.
- Exceptional score reduction. A round far better than your index won't trigger an extra cut.