What "Daily Revision" Actually Means
Every day the system rebuilds your index from the current last-20-round window:
- Each round produces a Score Differential:
(Adjusted Gross Score − Course Rating) × 113 ÷ Slope Rating. - The lowest 10 of your last 20 differentials are averaged.
- The result is rounded to one decimal — that's your index, refreshed daily.
So a great round doesn't just add a good differential; it can also push your oldest differential out of the window, which matters when your history contains a bad score you'd love to forget.
What Does NOT Change Daily
- Course Handicap — it's recalculated from your current index whenever you play, but only changes when the index or the course's ratings change.
- Your best 10 differentials — the underlying scores stay until they age out of the last-20 window.
Use the course handicap calculator to see how today's index translates into strokes.
Practical Timelines
| Event | Typical timing |
|---|---|
| Score posted today | Index updated next revision cycle (daily) |
| First index (5th round) | Within a day or two of the 5th qualifying round |
| New course handicap before a round | Recalculated the moment you check it with a current index |
Common Mistakes
- Expecting a monthly "update day". Daily revision means your index is almost never a month old.
- Forgetting the 20-round window. An old great round that leaves the window can raise your index even if you haven't played.
- Confusing index updates with course handicap changes. The two move on different triggers.
Frequently Asked Questions
Can my index change without me playing?
Yes — when a score ages out of the last-20 window, your best-10 average is recalculated even if you haven't teed it up.
What time does the daily revision happen?
It varies by association, but revisions typically run overnight, so checking in the morning reflects your newest scores.
Do 9-hole scores update the same way?
Yes — they're paired into 18-hole equivalents and treated like any other round in the daily calculation.
Watch your number move
Log rounds and see your index update automatically after every score.
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