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How do handicaps work for 9-hole and 18-hole golf event

Keith Moehring
November 18, 2023
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Applying handicaps to a round of golf isn't not confusing. This is especially true when switching between 9-hole and 18-hole rounds. The course and player information used is different. 

Below is a breakdown of how handicaps are calculated and what information you need to enter into PlayThru so that handicaps are applied correctly. 

Straight Handicaps or Adjusted Handicaps

First off. Much of this article applies to adjusted handicaps. Adjusted handicaps are when you take a player's handicap and adjust it for the difficulty of the course. 

You don't necessarily need to do this. You can play with straight handicaps. In which case, you'd apply the full handicap for an 18-hole round, and you'd divide the player handicap by 2 for 9-hole rounds. 

If adjusting your handicaps for the course, read on. 

18-Hole Adjusted Handicaps

Adjusting handicaps requires the golf course's Slope Rating and Course Rating, along with the Total Par. These values are then applied to the player's handicap using the following formula.

Adjusted Handicap = Handicap x (Slope Rating / 113) + (Course Rating - Total Par)

For example, if I'm a 10 handicap playing on a course with a slope rating of 121, a course rating of 73 and a total par of 72, my adjusted handicap would be 11.7 (rounded to 12). 

10 x (121 / 113) + (73 - 72) = 11.7

PlayThru will do this calculation automatically within our system if you check the "Adjust Handicap" circle in the Event Tab of the Outing Organizer. 

9-Hole Adjusted Handicaps

If you're playing a 9-hole round, you need to make some adjustments. A golfer with a 12 handicap shouldn't get all their strokes over 9 holes. 

All courses have separate Slope Ratings and Course Ratings for each 9 and the full 18. Generally speaking, the 9-hole ratings are about half the ratings for the full 18, but not exactly. Usually, one 9 is harder than another, and the slope and course ratings reflect that. 

The 9-hole ratings sometimes appear on the course's scorecard, but more often than not, you need to ask the course for that information. 

To adjust a golfer's handicap for a 9-hole round, you need to use the following formula. 

Adjusted Handicap = (Handicap / 2) x (9-hole Slope / 113) + (9-hole Course Rating - Total Par)

For example, I'm still a 10 handicap and playing on a 9-hole course with a slope of 61.5 and a course rating of 37 with a par of 36. My adjusted handicap will be 3.7 rounded to 4. 

(10 / 2) x (61.5 / 113) + (37 - 36) = 3.7

PlayThru will NOT divide handicaps by two, or adjust the slope and course ratings automatically. You'll need to enter the correct information. However, PlayThru will apply the correct formula to adjust golfer handicaps for the course if you check the "Adjust Handicap" circle in the Event Tab of the Outing Organizer. 

In other words, you enter the following:

  • Handicap: golfer handicap / 2 (Golfer Tab)
  • 9-hole slope rating (Course Tab)
  • 9-hole course rating (Course Tab)

From there, PlayThru will apply the correct formula to adjust the player's 9-hole handicap for the course. 


Rounding Rules

In both 18-hole and 9-hole calculations, the final Course Handicap is rounded to the nearest whole number, with .5 rounded upwards. This rule is important for adjusting maximum hole scores and calculating score differentials, ensuring consistency and fairness in your game.

USGA v. World Handicap System

It's important to note, the above formulas are contingent on what set of rules you follow. The above are the rules as defined by the USGA. However, the World Handicap System sometimes uses different formulas. Namely, they don't add (course rating - par).  


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