What is Slope and Course Rating
Course rating is a numerical value given to each set of tees at a particular golf course to approximate the number of strokes it should take a scratch golfer to complete the course. For example, if there is a course rating of 74.8, it means that scratch golfers are expected to post an average score of 74.8 from that set of tees on that course.
Course ratings are different from different sets of tees and play a key role in determining a golfer's handicap index in the USGA Handicap System.
Slope rating is different from course rating and is a measurement of the difficulty of a golf course for bogey golfers relative to the course rating. The main difference being that course rating tells scratch golfers how difficult the course will be whereas slope rating tells bogey golfers how difficult it will be.
The minimum slope rating is 55 and the maximum is 155, wherein these numbers do not relate to the number of strokes taken as course rating does. The slope rating for a golf course of average difficulty is 113. Slope rating is calculated for each set of tees on a course and is used to calculate the handicap index as well as the course handicap.
Slope rating helps in leveling the playing field for players of different skill levels. For example, let's say Player A and Player B average 85 strokes each for 18 holes. But Player A's average is established on a very difficult course (say, a slope rating of 145), while Player B's average is established on a very easy course (say, a slope rating of 95). Clearly, Player A is the better golfer, and in a match between the two Player B would clearly need some strokes, even though they may have the same handicap
Slope rating allows the handicap index to reflect these factors. Because he plays on a course with a higher slope rating, Player A's handicap index will be lower than Player B's (when it is calculated using the slope ratings), despite the fact that they both average scores of 85.