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 Course Rating. The lowest Slope rating is 55 and the highest is 155. A golf course of standard playing difficulty has a USGA Slope Rating of 113. If a course has a high Slope rating, it is relatively more difficult for the average golfer than a course with a low Slope Rating. The USGA Slope Rating is a mathematical measurement of how “proportionately” more difficult a set of tees is for those golfers who are not scratch golfers as opposed to the scratch golfers. The greater the difference in the two ratings, the higher the Slope Rating.
USGA Slope Rating = (Bogey Course Rating-USGA Course Rating) x 5.381 for men or 4.24 for women. While many have been conditioned to equate the USGA Slope Rating to the overall difficulty of a golf course, it is not the whole factor. In fact, to really determine the overall difficulty of a golf course you must first compare USGA Course Ratings. A golf course with a USGA Course Rating of 69.0 is less difficult for all golfers than one rated at 71.0 even if they have the same Slope Rating. Since they both have the same USGA Slope Rating (125), they both have the same difference between the scratch and bogey golfers, 23.2 stokes. Even though both courses have a Slope rating of 125, the bogey golfer on the course rated at 69.0 will average 92.2 in his best 10 scores while his counterpart on the course rated at 71.0 will average 94.2 If all golf courses had the exact same USGA Course Rating, the course with the highest USGA Slope Rating would be the most difficult course on which to score. But since all courses do not have the same USGA Course Rating, you must evaluate both the Course and Slope Rating, to determine which course is the most difficult on which to score. It is highly possible that you may have a course that has a lower USGA Slope Rating than another course, yet is more difficult to score on because its USGA Course Rating is higher than that of the higher Sloped course. The Course Rating for either the scratch or bogey golfer is determined by adding the yardage rating to the obstacle stroke value for that golfer.
Scratch Yardage Rating (Male) = (Scratch male effective playing length/220) + 40.9
Scratch Yardage Rating (Female) = (Scratch female effective playing length/180) + 40.1
Bogey Yardage Rating (Male) = (Bogey male effective playing length/160) + 50.7
Bogey Yardage Rating (Female) = (Bogey female effective playing length/120) + 51.3