First, the definition:

A “Handicap Index” is the USGA’s service mark used to indicate a measurement of a player’s potential ability on a course of standard playing difficulty.  It is expressed as a number taken to one decimal place.

Now that you know the definition, let’s go through the USGA handicap formula:

Step 1:  Determine the number of handicap differentials to use (see “Ever wonder what the Course Rating and Slope Rating represent” on “handicap differentials”).  Under USGA handicap system, you need to submit at least five scores before the handicap index may be calculated.  Some local clubs/association may demand more scores to be submitted because the accuracy of the handicap index is directly proportional to the number of acceptable scores submitted.  For illustration purpose, let’s use 20 scores.

Step 2:  Calculate your handicap differentials ((adjusted gross score – course rating) x 113 / slope rating)

Step 3:  Average the number of handicap differentials being used.  You do not average ALL the handicap differentials submitted.  If you submitted 20 scores, you will only average the 10 lowest handicap differentials.

Step 4:  Multiply the average by 0.96 (this factor is known as the Bonus for Excellence. It is the incentive for players to improve their golf games)

Step 5: Delete all number after the tenths’ digit.  Do not round to the nearest tenth.

Example:

Total of 10 lowest handicap differentials (from the most recent 20 scores submitted) = 154.8

Average = 15.48

Multiply by 0.96 = 14.861

Delete all digits after tenths = 14.8

This is your handicap index … 14.8

Noticed how the formula only picks your 10 lowest handicap differentials from 20 scores submitted?  So the next time you play a terrible game, don’t forget to submit your score.  Submission of scores is mandatory and if it is an anomaly, rest assured that it will not be taken into account in calculating your handicap index.

In addition to the above, there is a provision under USGA Handicap System to reduce the Handicap Index calculated by the above method if the player posted exceptional tournament scores.  We’ll save that for later.

Enjoy your game!

David

(reference: USGA Handicap System 2008-2011)

Well, let’s decode it:

1. Definition

Course Rating (or USGA Course Rating) is the USGA’s mark that indicates the evaluation of the playing difficulty of a course for a scratch golfer under normal course and weather conditions. In short, it reflects the probable score of a scratch golfer playing on the course. So the higher the number, the more difficult is the course.

Slope Rating is the USGA’s mark that indicates the measurement of the relative difficulty of a course for players who are not scratch golfers compared to the USGA Course Rating. The lowest Slope Rating is 55 and the highest is 155. A golf course of standard playing difficulty has a Slope Rating of 113. The higher the number, the more difficult is the course for players who are not scratch golfers.

Confused? Don’t worry, the explanation below is more intuitive.

2. When and how do we usually apply them?

Well, when you need to compute your handicap differential for the round you just played. We beginners tend to think that if we shoot a 95 on a par 72, 18-hole round, our handicap differential is 23 (i.e. 96 less 72). Not exactly. Doing so would not have taken into the account the absolute and relative difficulty of the course, i.e. shooting a 95 on one relatively easy course is not the same as shooting the same score on a more difficult course. So the right formula to compute your handicap differential for the round is:

(Adjusted Gross Score – USGA Course Rating) x 113 / Slope Rating

*never mind what is “Adjusted”, I’ll explain that another time.

For example, if you shoot a gross score of 95 on a course with Course and Slope ratings of 71.5 and 125 respectively, your handicap differential would be:

(95 – 71.5) x 113 / 125 = 21.2 (rounded)

See how the result of 21.2 differs from what you would normally compute as 23? You actually played better (a lower handicap differential) than you think, after taking into account the difficulty level of the course.

The USGA Course Rating is also used to determine the strokes to receive or give when competing from different set of tees. But I think the above is enough for now. Save that for next time.

Hope this helps make you a more ‘informed’ golfer when you next tee-off.

David

(reference: USGA Handicap System 2008-2011)