What is stroke index in golf?

When you’re starting your golfing journey or playing for the first time, it can be challenging to wrap your head around the many golf-specific terms that are necessary throughout a round. Of these terms, the stroke index is one of the most important. Put simply, this is the means by which the difficulty of a course and its 18 holes are ranked.

Keep reading to discover how this stroke index in golf is applied to a course, what it means in relation to your handicap, and how it differs from other similar terms you may hear on the course.

What is a stroke index?

The simplest way of understanding the stroke index (or SI as it is also known) is as a ranking of how hard it is to complete each hole on a course. As a general rule, holes will be ranked from most difficult to easiest to complete. So, the hardest hole on the course will receive a stroke index of one, while the simplest will be 18. Put simply, the harder the hole, the lower it is on the stroke index.

Many factors contribute to assessing which holes are difficult and which are ‘easy’. It’s important to note that the stroke index is relative to the par of a particular hole, so it’s not as simple as saying a higher par results in a lower stroke index. Hazards and terrain variation, such as elevation and the positioning of boundaries, play a significant role in determining which holes are ranked highly and which are ranked lowly on the stroke index. As such, a hole that is simply further away from the tee than another might not necessarily be ranked further down the stroke index.

Typically, holes with high and low stroke indexes are distributed evenly from front to back. This means it’s usually the case that the front nine holes and the back nine holes are relatively similar in difficulty. For example, holes with stroke indexes of one and two are likely to be split between the first and second sets of nine holes. Which holes are ranked highly and lowly, and where they’re located on the course, are determined by the committee.

How does the stroke index affect handicaps?

Another important reason for the stroke index is to ensure that two players of differing abilities can compete with one another on a more level playing field. This is where handicaps come in.

In stroke play, it’s very simple. All you need to do is subtract your handicap from the total number of strokes across the 18 holes (your gross score) to find your net score. Then, the lowest net score wins. Say you completed the course in 80 strokes and had a handicap of 10, you’d finish with a net score of 70. However, in formats like match play and Stableford, this is slightly complicated because strokes are deducted depending on the stroke index of a hole.

In short, with that handicap of 10, you’d deduct a stroke from the holes with stroke indexes one to 10: the 10 most difficult. So, if you were to finish with a score of six on any of those 10 most challenging holes in a round of match play, it would be reduced to five. This means golfers with higher handicaps have a chance to compete with those with lower ones, who will have a stroke subtracted on fewer holes.

If your handicap is over 18, you’ll receive extra subtractions. Say your handicap is 22, you’ll take two shots at the holes ranked one to four (because 22-18=4). For the remaining 14 holes, you’ll take away one shot. The highest handicap a golfer can have is 28, meaning they’d get a significant advantage over their opponent. All of this is to say that a player with a high handicap could, in theory, play a round against a stronger golfer and still have a chance of winning or playing a competitive game.

The difference between stroke index, course rating and slope rating

It’s important not to confuse the stroke index with course and slope ratings. All three of these terms are used to assess difficulty, but they do so in different ways.

• The course rating pertains to how difficult it would be for a scratch golfer (a golfer with a handicap of zero) to complete the course. It’s a simple metric to understand, because it’s measured in strokes. For example, a course rating of 70 means a scratch golfer would be expected to complete the course with an average score of 70 strokes.
• A slope rating is a little more complicated because it’s relative and refers to the difference between the average strokes expected of a scratch golfer to complete the course and a bogey golfer. Each course has its course rating and its bogey rating, and the combination of the two is what creates the slope ranking. It can range from 55 to 155, but is more likely to be around 110.

In short, the slope and course ratings refer to the entire course. The stroke index refers to each individual hole.

The benefits of a stroke index

What’s great about the stroke index is that it was designed for match play, and its relativity to the difficulty of each hole means your handicap has a more specific impact on the outcome of your round.

Without it, a round of match play would be as simple as giving the ‘stronger’ golfer an all but guaranteed victory. But, with the stroke index in play, the player with the high handicap has a chance not only of winning the round as a whole but also of completing some of the most challenging holes in a more favourable number of strokes.

This is why it’s great for players just getting into the game. Though it may sound difficult, once you understand how it works, you’ll be putting your best foot forward.

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