Many golfers, when asked that question, won’t be able to give an accurate answer. If you play regularly it’s a good thing to know. The purpose of the system has always been to attempt to level the playing field for golfers with various abilities. I’ll bet most golfers don’t really understand how it’s calculated.
Terminology
There are a few terms you need to know to truly understand the handicapping calculation. A Handicap Index, issued by a golf club or golf association, compares a player’s scoring ability to a scratch golfer on a course of average difficulty. This number reflects a player’s potential score and is based on the best 10 of the last 20 rounds. A USGA Course Rating indicates the playing difficulty of a course for a scratch golfer based on yardage and other features. “A Slope Rating is a measurement of the relative difficulty of a course for players who are not scratch golfers. Each course is rated from each set of tees for both the scratch golfer and the bogey golfer.”[i]
What this means
To put it simply, your handicap index suggests your potential score on a course of standard difficulty, meaning a slope rating of 113. Slope ratings range from 55 to 155. When you play a course with a slope rating higher than 113, your Course Handicap will be higher than your handicap index. For example, if you have a handicap index of 10 and you are playing Pebble Beach with a slope rating of 144, your course handicap is 13. If you are playing a much less difficult course with a slope rating of say 90, your course handicap is 8.
A handicap index makes it easier and more fun to compete with other golfers, it also helps you measure your progress in developing skill. Later on, if you get really good and want to qualify for the U.S. Open, you will need a USGA Handicap Index of 1.4 or lower.[ii] Good luck!
[i] http://www.usga.org/Handicapping/handicap-manual.html#!rule-14367
[ii] http://usga.usopen.com/qualifying/eligibility.html