How Is Course Difficulty Measured?

We will all have played golf courses and come off thinking, ‘That was hard’, or occasionally even, ‘That was easy’. But just what is it that makes a golf course hard or easy?

Obviously, we can come up with reasons one way or the other based on our experiences – for example, lots of long holes, narrow fairways, thick rough, tricky greens and so on one way; plenty of room to miss it, relatively few hazards of any type and flat, undefended greens the other way.

Some courses have a reputation for difficulty – St Mellion in Cornwall, for example, or Carnoustie up in Angus – but under the World Handicap System introduced in 2020, rather than mere reputation, it is the Course Rating and Slope Rating that seek to quantify the degree of difficulty as objectively as possible in a way the old Standard Scratch Score scheme perhaps never quite could.

Course Rating (playing difficulty of a course for the scratch golfer) and Bogey Rating (playing difficulty for a 20- to 24-handicapper) now combine to determine the Slope Rating, which in turn dictates how many shots you get on a given course (your Course Handicap) based on your Handicap Index.

If you get more shots than your index, it will be because the Slope Rating for the tees you are playing from is higher than average and therefore the course has been rated as more difficult than average (and vice versa of course). Slope Ratings can range from 55 to 155 with a golf course of standard relative difficulty having a Slope Rating of 113.

Course Rating and Bogey Rating

The keys to measuring course difficulty are Course Rating and Bogey Rating. The former is calculated via the 'effective playing length' and 'obstacle factors' for the course (more of which below) and is expressed in strokes to one decimal point. The difference between that and the Bogey Rating determines the Slope Rating.

Par and course length alone are just not accurate enough indicators of course difficulty, although course length undeniably has a bearing. The WHS Course Rating System is highly objective and takes into account all of the factors that might affect playing difficulty, including, of course, some of those mentioned anecdotally at the start here.

Course Rating teams use a comprehensive Course Rating System Guide that asks them to consider 460 variables on a standard course rating, from each set of tees. It uses table values, adjustments and formulas to calculate ratings and requires numerous specific measurements on each hole to ensure a very high degree of consistency among different course rating teams.

Of course, length is part of it – we all know that. But beyond that, the teams consider several factors that can further influence the playing length of the course along with ten ‘obstacle factors’ that affect the playing difficulty of each hole.

Factors influencing effective playing length

Roll
How much fairway roll will you get depending on surface conditions and contouring?

Doglegs
Might a hole with a dogleg design prevent or discourage a full tee shot being played?

Wind
What is the strength and direction of the average or prevailing wind?

Elevation changes
How will differences in elevation between tee and green and on approach shots affect how far the ball goes?

Forced lay-ups
Do various obstacles that cross the fairway force you to play short of them?

Altitude
Balls fly further at higher altitude – does that have any bearing on effective playing length?

The 10 obstacle factors

Topography
What sort of stance and lie are you likely to get in the landing zone and do elevation changes impact on the approach shot?

Fairway
How wide are the fairway landing zones and how close the nearby obstacles, whether trees, penalty areas, bunkers or rough?

Green target
How easy or hard is it to hit the green, how receptive is the green and how visible is it for the approach shot?

Recoverability and rough
How easy or difficult is the recovery if you miss the intended tee-shot landing zone or green?

Bunkers
How big and deep are the bunkers and how close to landing zones and greens?

Lateral obstacle
How far away from the centre of fairways and greens are any lateral obstacles?

Crossing obstacle
How far is it to safely carry water, penalty areas, OOB or testing rough or heather?

Trees
How big, tall and dense are trees or woodland and how close to the centre of landing zones and greens? How difficult is the recovery from them?

Green surface
How testing are the greens in terms of speed, contouring, tiers etc?

Psychological
What impact do the other nine obstacle factors have on your mental game – do they put you under extra pressure or allow you to breathe relatively easily?

As with many rankings and ratings, it will never be a precise science and we will all have played courses where the Course Rating or Slope Rating raises eyebrows one way or another. But, as you can see, it isn’t for any lack of desire to be as objective and thorough as possible when measuring the difficulty of a golf course.