Why My Handicap Jumped from 11 to 15 — And What Every 9-Hole Golfer Should Know
Until recently, I thought I had a pretty good handle on my golf game. According to The Grint, where I log all of my rounds, my Handicap Index had settled around 11. At the end of last season, when I started this blog, it had gotten down to 10, thus the title of the blog being my journey from 10 to Scratch. 11 is far from scratch, but respectable — especially for someone who gets busy, and tries to squeeze in 9-hole rounds on the weekends or after work.
I had been debating getting an official handicap. I have no real reason to get one, aside from having a way to monitor my progress. GHIN was offering a free one month trial, so I figured, “Why not?”
So, I got the free 30 day trial on the official GHIN website — the one that’s tied directly to the USGA’s World Handicap System — and I was confused. It said my estimated index was listed as 15.
I thought maybe there was something odd with the free trial. In the free trial, I wasn’t able to see how it calculated my index for each round. I was thinking maybe if I got the paid version, the handicap calculations would be done more precisely and it would match my Grint handicap. I had been planning to get an official paid handicap eventually and decided now was as good of a time as any. I paid the $50 to the Chicago District Golf Association, and sure enough, it showed my handicap is currently a 15. I was mostly disappointed that I clearly am not as good as I thought I was. But I was also confused as to why there was such a big difference.
How could there be a four-stroke difference?
After digging in, I discovered that a major rule change took effect in January 2024, and it’s dramatically reshaping how 9-hole rounds affect your handicap. If you’re like me and play a lot of 9-hole rounds, you need to understand this update — because it might be inflating your official index too.
The 2024 Rule Change: How 9-Hole Scores Are Now Treated
Before 2024, the World Handicap System would only include your 9-hole scores in your index once two 9s were paired to create an 18-hole Score Differential. So if you played a solid 9 on Monday and didn’t get another one in for two weeks, your handicap stayed unchanged until that second round was posted.
That’s no longer the case. As of January 2024, once you post a valid 9-hole round to GHIN, it immediately counts toward your handicap. But there’s a twist: instead of waiting for a second 9-hole score, the system now adds an expected Score Differential for the other 9 holes based on your current Handicap Index.
Here’s the official explanation from the USGA: 2024 9-Hole Scoring Changes FAQ
Why This Shift Mattered for Me
I realized that many of the 9-hole rounds I had posted to The Grint — which didn’t apply this expected-score rule — were counting toward my average in a more favorable way. When I had a strong 9-hole performance, The Grint would just double the score and count it as if it were an 18 hole round.
Now, GHIN sees that same solid 9-hole round and says, “We’ll assume you played your average on the back nine,” and plugs in a formulaic expected score that may not reflect how I was actually trending.
In practice, that means my good 9-hole rounds get blended with average performance, which raises the resulting differentials — and thus my index.
Real-World Example From My Scores
Here’s one example:
I shot a 41 on a par-35 front nine — a typical decent round for me.
That 9-hole score translated to a Score Differential of about 6.0 for the 9 holes. The Grint would double that to make an 18 hole Score Differential of 12.0.
Under the new rule, GHIN added an expected back nine based on my 15.4 index prior to that round. The resulting full 18-hole differential was 15.3.
Multiply that across several rounds, and boom — I’m no longer an 11. I’m a 15.
Why It Still Makes Sense (Even If It Hurts)
After the initial sting wore off, I have to admit the logic is sound. The new approach prevents people from pairing two lucky 9-hole rounds and skewing their handicap. It also ensures that frequent 9-hole players — like me — get real-time updates instead of waiting for that second half to show up. And it also made clear how the way the Grint handles 9 hole scores is problematic and does not give an accurate reflection of my true handicap.
It’s just a tough pill to swallow when you feel like your best rounds are being “watered down” by an expected score you didn’t actually play.
What You Should Do
If you use third-party apps like The Grint, 18Birdies, or SwingU, and your index looks much lower than what GHIN shows, this rule change is likely the reason. GHIN is now the only place showing your true official Handicap Index under the updated 2024 rules. At least I was not able to find a free way to accurately calculate an 18 hole Score Differential for 9 hole rounds.
Other Places Discussing this Change
I was able to figure this out due to the help I read on a few different sites.
First, I finally found the formula to accurately calculate an 18 hold Handicap Index from a 9 hole round in this thread on GolfWRX.
The official formula to calculate the back 9 is 0.52 * Handicap Index + 1.2
That is why in my example above, GHIN took my 6.0 and added 9.3 to get 15.3.
15.4 (my handicap prior to that round) * 0.52 + 1.2 = 9.2
So, somewhere there must have been rounding, that my front 9 (approx 6.0) added to 9.2 gave the GHIN result of 15.3
Based on this information, it seems like websites like The Grint should be able to accurately calculate someone’s handicap.
Final Thoughts
The new rule is a double-edged sword. It’s more modern, more responsive, and better for people who play lots of 9-hole rounds. But if you’ve been coasting on paired 9-hole scores, don’t be surprised if your official index jumps.
If anything, it’s motivation to play more full rounds — or at least know what’s really happening behind the scenes when you tap “Post Score.”
Bottom line: Don’t panic. Just be aware. And maybe bring your best swing for all 18 — or at least the 9 you do play.
Thanks for reading, and if you’ve had a similar experience, I’d love to hear how this change has affected your own index!
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