What Is SI in Golf?

Ever glanced at a golf scorecard and seen the column labeled SI or Handicap and wondered what those numbers, 1 through 18, actually mean? You’re not alone. The Stroke Index, or SI, is a fundamental part of a handicap golf round, yet it’s one of the most frequently misunderstood concepts. This guide will clearly explain what the Stroke Index is, how it’s determined, and most importantly, how you can use it to play smarter, manage the course better, and win more of your matches.

What Does SI (Stroke Index) Actually Mean?

The Stroke Index (SI) is simply a ranking of the holes on a golf course from 1 to 18 in order of difficulty. It’s a way to numerically represent how challenging each hole is relative to the others on that same course.

Here’s the basic breakdown:

• SI 1: Designates the hardest hole on the course.
• SI 18: Designates the easiest hole on the course.

Every number in between fills a spot on that difficulty spectrum. The hole with the "SI 2" is the second-toughest hole, the "SI 10" is the tenth-toughest, and so on. Its primary function is to determine where handicap strokes are given and received in various forms of 'net' golf competitions, like match play or Stableford.

It's important to remember that 'difficulty' in this context isn't just about length. While a long Par 5 is often challenging, a short, tricky Par 3 with a tiny, well-guarded green and a lake could easily be ranked as one of the hardest holes. The SI takes into account all factors that can lead to a higher score, such as fairway width, the presence of hazards like water and bunkers, green complexity, and even typical wind conditions.

How is the Stroke Index Determined?

The SI ratings aren't just arbitrarily assigned by the course pro. They are the result of careful analysis by the golf course committee or the local golf union. The process involves collecting long-term data on how golfers of varying abilities actually score on each hole.

The goal is to identify the holes where there is the biggest difference in score between a high-handicap golfer and a scratch golfer. The holes that create the most separation in scores are typically the ones that receive the lowest Stroke Index numbers (e.g., SI 1, 2, 3).

You may also notice a very specific pattern in how the numbers are distributed. To ensure strokes are spread out evenly throughout a round, the recommendations from governing bodies like the USGA or R&,A suggest allocating odd SI numbers to one nine and even SI numbers to the other. For example:

• SI 1, 3, 5, 7, etc., might be on the front nine.
• SI 2, 4, 6, 8, etc., will then be on the back nine.

This prevents a player receiving, say, seven strokes from getting all of them on the first seven holes. Splitting them up ensures a fair distribution from beginning to end, which is especially important in match play.

The Main Event: How to Use the Stroke Index in Your Game

This is where the theory turns into practical, on-course application. Understanding the SI is your secret weapon in handicap formats. Let's look at the most common ones.

Using SI in Match Play

Match play is where the Stroke Index truly takes center stage. In this format, you are competing against another player on a hole-by-hole basis. The SI dictates where a player with a higher handicap gets an advantage.

Let's walk through an example:

1. Calculate the Difference: Player A has a Course Handicap of 12. Player B has a Course Handicap of 20. The difference is 8 strokes (20 - 12 = 8).
2. Allocate the Strokes: The higher handicap player, Player B, receives these 8 strokes.
3. Apply to the Scorecard: Player B will get one stroke on the 8 most difficult holes, which are the holes with a Stroke Index of 1, 2, 3, 4, 5, 6, 7, and 8.

Now, let's see this in action on the course.

• On the 4th hole, a Par 4 with an SI of 5, Player B gets a stroke. If Player A makes a 4 and Player B makes a 5, their scores are tied for that hole because Player B’s net score is 4 (5 - 1 = 4). The hole is halved.
• On the 11th hole, a Par 3 with an SI of 14, no strokes are given. If Player A makes a 3 and Player B makes a 4, Player A wins the hole. Their gross scores are what count.

Being aware of these "shot holes" before you tee off is fundamental to building a match play strategy.

Using SI in Stableford

Stableford is a points-based game where you're trying to score the highest point total, not the lowest stroke total. Your Course Handicap determines your "par" for each hole.

Here’s how it works with a Couse Handicap of 22:

1. Strokes Per Hole: With a handicap of 22, you get more than one shot on some holes. You get at least one shot on every single hole (that covers 18 of your 22 handicap strokes).
2. Allocating Extra Strokes: You have 4 extra strokes left over (22 - 18 = 4). These are given to you on the hardest holes: SI 1, SI 2, SI 3, and SI 4. On these four holes, you receive 2 strokes.

Let's look at an example. You are playing the 6th hole, a Par 5 with an SI of 2.

• You get two strokes on this hole. Your net par is a 7 (5 + 2).
• If you shoot a 6 on the hole, your net score is a 4 (a net birdie). In Stableford, a net birdie earns you 3 points.
• If you shoot a 7, your net score is a 5 (a net par), earning you 2 points.
• If you shoot an 8, your net score is a 6 (a net bogey), earning you 1 point.

Knowing your net par for each hole simplifies Stableford and helps you chase points intelligently.

Using SI in Regular Stroke Play (Medal)

In standard stroke play (often called medal play), your handicap is just subtracted from your gross score at the very end to determine your final net score. At first glance, the SI seems less relevant here, but strategically, it's just as important.

Knowing the SI helps you manage your expectations and on-course decisions. If you're a 15-handicapper, you know that a bogey on any hole with an SI of 15 or less is effectively a "net par."

Think about this: approaching the SI 1 hole, the hardest on the course, your mindset shouldn't be "I need to make a par." Instead, it should be, "What's the safest way to make a bogey?" This small mental shift encourages smarter play, taking risks out of the equation on holes where danger lurks.

Strategic Thinking: Making the Stroke Index Work for You

Moving beyond the rules, the SI is a powerful tool for course management for any golfer who carries a handicap.

Know Where to Be Aggressive vs. Conservative

Before you even hit your first shot, review the scorecard. Mentally circle the holes where you get strokes. These are your "opportunity" holes, but not necessarily for making birdies.

• On a "Shot Hole" (Low SI): Your primary goal is to avoid blow-ups. A triple bogey on a hole where you get a stroke can ruin your score. Play more conservatively. Aim for the center of the fairway and the middle of the green. Making a net par is a win.
• On a "Non-Shot Hole" (High SI): These are often shorter or less perilous holes like the SI 17 or 18. This is where you might take a slightly more aggressive line off the tee or fire at a specific pin location if you're feeling good about your game.

Build a Course Management Mindset

Using the Stroke Index gets you out of the habit of just looking at the par of a hole. You start to see the course through a strategic lens, just like a professional caddie would.

For example, you’re an 18-handicapper standing on the tee of a 400-yard Par 4 with water all down the left and trees right. It’s the SI 1 hole. Instead of automatically pulling the driver hoping to get close, you recognize you get a stroke. Your goal is a net par, which is a gross bogey 5. A smarter plan might be:

1. Hybrid off the tee for control, leaving you 180 yards out.
2. 7-iron to the front or middle of the green.
3. Two putts for a "good bogey" 5.

That kind of thinking saves you from the hero shot that often leads to a 7 or an 8. Over 18 holes, this disciplined approach will dramatically lower your scores.

Common SI Questions Answered

Let's quickly clear up a few common points of confusion.

• Does SI Mean Length? Not always. While many long holes have low SIs, factors like tight fairways, unavoidable forced carries, treacherous greens, or prevailing winds can make a shorter hole extremely difficult and earn it a low SI rating.
• Is the Stroke Index the Same for Men and Women? Usually not. Most courses have separate SIs for the men's and women's tees. This is because a hole's difficulty can change drastically from different tee boxes. A hole that is a simple flick for a man might be a tough, long iron approach for a woman, and the SI ratings will reflect that.
• Does the SI Ever Change? Yes. Golf courses are encouraged to review their Stroke Index allocations every few years to ensure they are still accurate. As tree lines grow, bunkering is changed, or data shows scoring patterns have shifted, the committee may re-rate the holes.

Final Thoughts

The Stroke Index is far more than just some arbitrary numbers on a scorecard. It's the engine of handicap golf, ranking a course’s holes by difficulty to ensure fair competition. By understanding what it means and how to apply it, you move from simply playing golf to thinking your way around the course, making smarter decisions that will lead to lower scores and more victories.

Knowing that a hole is SI 3 is a great start, but figuring out the best way for you to play that specific hole in real-time is the next step. This is where we come in. With Caddie AI, you can get an instant, personalized strategy for any hole based on its layout and your game. We'll help you turn that SI knowledge into an actionable plan, giving you the kind of on-demand advice that removes guesswork so you can step up to every shot with clarity and confidence.