How Course and Slope Ratings are calculated

How Course and Slope Ratings are calculated

When it comes to calculating your golf handicap, two essential factors come into play: the course rating and slope.

These numbers are vital in assessing the difficulty of a golf course.

  • The course rating represents the expected score for a scratch golfer (someone with a handicap of 0),
  • while the slope signifies the increased level of challenge for a bogey golfer (a player with a handicap of 18) in comparison to a scratch golfer.

Course Rating

You might think that the course rating involves a team of scratch golfers playing the course and averaging their scores.

However, in reality, no actual playing is involved in this process.

The rating is determined primarily by a yardage formula with slight adjustments for obstacles.

The reason for this is that yardage has the most significant impact on the performance of a scratch golfer.

Challenges like woods on the right or water in front of the tee don’t pose a significant threat to them.

Still, the difference between trying to make a birdie from 120 yards compared to 160 yards can be substantial.

To calculate the Course Rating, the governing bodies use an imaginary ideal scratch golfer who can:

  • drive the ball 250 yards (including 225 yards of carry and 25 yards of roll)
  • can hit their second shot 220 yards (200 and 20)
  • This golfer has a tendency to draw the ball
  • and excels in all aspects of the game.

The Scratch Yardage Rating is a relatively straightforward calculation.  It’s essentially the course yardage divided by 220, with an addition of 40.9.

This rating may be adjusted for various factors like the distance the ball rolls, the number of elevated or dogleg holes, prevailing wind conditions, and altitude.

Any factor that affects the scratch golfer’s profile (making them hit farther or shorter than 250 yards) influences the Scratch Yardage Rating.

The Scratch Obstacle Rating, on the other hand, is a more complex calculation.

It involves evaluating each hole using a form with 11 boxes for each hole.  These boxes are filled with numbers representing obstacle values, with the standard value set at 4.

A lower value indicates less difficulty posed by obstacles, while a 10 suggests a very challenging hole.

Obstacles considered for each hole include:

  1. topography
  2. fairway
  3. recoverability
  4. rough
  5. out of bounds
  6. water hazards
  7. trees
  8. bunkers
  9. the green target
  10. green surface
  11. and even a psychological factor.

Each of these elements is given a weight, and the sum of the weighted values for all 18 holes is multiplied by 0.11.

This result is then adjusted by subtracting 4.9 to determine the Scratch Obstacle Rating.

The Course Rating is the sum of the Scratch Yardage Rating and the Scratch Obstacle Rating.

Yardage vs. Obstacle Ratings

While over 95% of the course rating is influenced by yardage, significant changes in course rating often stem from obstacles.

For example, if a course were to become 400 yards longer, the Scratch Yardage Rating would increase by just 2.6%.

In contrast, if the obstacles on the course (typically rated 4) became considerably more challenging (rated 8), the Scratch Obstacle Rating could increase by over 250%.

Course Slope

For the slope, there’s no actual game-play involving bogey golfers to determine the score.

Similar to the course rating, they have also created a model bogey golfer.

This model represents a golfer with a Handicap Index of 17.5 to 22.4.

  • They can hit tee shots an average of 200 yards
  • and can reach a 370 yard hole in two shots.

The slope is determined by two key factors: the Bogey Yardage Rating and the Bogey Obstacle Rating.

The Bogey Yardage Rating is based on yardage as well but uses a different formula: it’s the course yardage divided by 160 plus 50.7

The Bogey Obstacle Rating, however, is based on the same 11 factors, weighted differently for each hole.

The sum of these factors for all 18 holes is then multiplied by 0.26, and 11.5 is subtracted.

It’s important to note that obstacles play a more significant role in the Bogey Obstacle Rating because the 0.26 factor is 2.5 times that of the 0.11 factor used for the Scratch Obstacle Rating.

The Bogey Yardage Rating and Bogey Obstacle Rating are combined to create the Bogey Rating.

One more calculation remains.

The difference between the Bogey Rating and the Course Rating is multiplied by 5.381 to determine the slope ([Bogey Rating – Course Rating] * 5.381 = slope).

This complex process brings the handicap system to a new level of accuracy across all handicaps, ensuring fairness and precision in the world of golf handicaps.

If you would like to find out more about handicaps be sure to read my guide How Golf Handicaps Work

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