I knew that golf involved simple mathematics: counting your strokes on each hole, adding them all up at the end, and subtracting your total score from the course par total to get your score “over par”. But this game got a little more complicated…

Course hole handicaps
I was looking into golf handicaps today, and trying to learn a little more about them. When I was at Chick Evans with Mike, he was explaining to me what the handicap number for each hole on the score card meant. The lowest number handicap (1) means that the hole is the hardest, and the highest number handicap (18) means the hole is the easiest. After looking at the handicap number for each of the holes, it makes sense that the par 5 holes will have the lowest handicap number, and the par 3 holes will have the highest handicap number.

After researching course hole handicaps, Mike was very close to being correct. Golf Digest published an article back in February 2004 called “Solving the mystery of a hole’s assigned handicap“, and it states:

The handicap ranking assigned to each hole on a course doesn’t necessarily reflect the difficulty of making a good score there. The lower-numbered holes are where higher-handicap players most need a stroke to halve the hole when competing with a better player.

Golfer’s handicaps
Course hole handicaps seem pretty simple to understand, but there are more to golf handicaps. After a simple search on the definition of a golf handicap, Wikipedia told me this:

A golf handicap is a numerical measure of an amateur golfer’s playing ability. It can be used to calculate a net score from the number of strokes actually played, thus allowing players of different proficiency to play against each other on somewhat equal terms.

That means next time I play with a non-noob, if we factor in handicaps, I have just an equal chance of winning. I like that.

So what is my handicap?
This is where the more complex mathematics comes into play. There are a couple of things that need to be taken into consideration when determining a player’s golf handicap:

  • The gross score (total score) from the most recent rounds
  • The course rating and slope rating for those rounds

There are also some terms that can be defined. A “scratch golfer” is a golfer who’s handicap is 0. A “bogey golfer” is a golfer who’s handicap is 18. Handicaps below 0 are known as “plus” handicaps.

A course rating is generally between 67 and 77, and marks the average “good score” by a scratch golfer. A course slope rating is a ratio that is generally between 105 and 155, and marks the difficulty of the course for a bogey golfer compared to a scratch golfer.

With these values, for each round of golf, you can determine the handicap differential (rounded to the nearest tenth) using this formula:

Handicap differential = (gross score – course rating) × 113 / (slope rating)

Knowing all of the handicap differentials for each round of golf, you can determine the handicap index. To find the handicap index, you take the average of the best 10 differentials of the last 20 rounds, and multiply it by 0.96. If the golfer has posted at least 5 rounds of golf, but fewer than 20, then the index is calculated using between 1-9 differentials (see the table in the Wikipedia article).

There is also a course handicap to calculate, which is the number of stokes to deduct from golfer’s gross score to determine the net score. The course handicap uses this formula (and rounds to the nearest whole number):

Course handicap = (handicap index) × (slope rating) / 113

The Wikipedia article also mentions something about equitable score control, but that’s a little too much for me to grasp right now.

Now… what is MY handicap?
Well, it turns out I need to play 5 rounds of golf to figure this out. After my fifth round, I’ll determine my approximate handicap (real handicaps are given out by the USGA).

To make the process of determining your handicap much simpler, there are many golf handicap calculators on the web.

Special thanks to all the Wikipedia authors who put that article togethers so I can better understand golf handicaps.