How to Determine the Golf Grip Core Size

Choosing a new set of golf grips seems simple enough, but a hidden detail - the grip's core size - can completely change the way your clubs feel and perform. This tiny measurement marked on the inside of the grip tells you its inner diameter and how it will fit on your shaft. In this guide, we'll walk through exactly what core size is, how to find the right one for your clubs, and how you can use this knowledge to customize your equipment for better golf shots.

What Exactly is Golf Grip Core Size?

Think of golf grip core size as the starting point for your connection to the club. It is simply the measurement of the inside diameter of the golf grip. This is a critical measurement because for the grip to be installed correctly, its inner diameter should have a specific relationship with the outer diameter of the golf shaft's butt end (the thickest part of the shaft where the grip goes).

This measurement is almost always displayed in inches. You can typically find it printed on the inside of the grip's lip at the opening. The two most common core sizes you’ll encounter are:

• .580"
• .600"

While manufacturers produce other specialized core sizes for different types of shafts (like undersize, junior, or specific graphite models), the vast majority of standard grips on the market will be either .580" or .600". For this reason, we will focus on these two common sizes and their interactions with most golf shafts a golfer would be playing with.

The golden rule is this: To get the advertised, standard size of a grip, you must match the grip's core size to the shaft's butt diameter. So, if you have a shaft with a .600-inch butt diameter, putting a .600 core size grip on it will give you that grip's standard thickness. If your shaft has a .580" butt, a .580 core grip achieves the same standard result. The fun - and the opportunity for customization - begins when you mix and match.

Why Core Size Makes a Huge Difference to Feel and Performance

This is where a simple measurement becomes a powerful tool. Mismatching the grip core size and the shaft butt diameter directly alters the final, installed thickness of the grip. It works in a very predictable way that club builders and knowledgeable golfers use to their advantage.

The logic is straightforward:

• Installing a SMALLER core grip on a LARGER shaft will STRETCH the grip, making the final grip THICKER.
• Installing a LARGER core grip on a SMALLER shaft means the grip is less stretched, making the final grip THINNER.

Here’s how it breaks down with the two most common sizes:

The Math Behind the Feel

Let's look at the two most common scenarios that arise if golfers don't pay attention when re-gripping their clubs or how a knowledgeable golfer can manipulate their grip size in a few simple ways.

Scenario 1: Putting a .580" Grip on a .600" Shaft

You’re forcing a grip with a smaller opening onto a wider shaft. The rubber has to stretch more to fit, which increases its outer thickness. A .580 core grip on a .600 butt diameter shaft will result in a grip that is approximately +1/64" larger than standard. This is basically the equivalent of adding one full layer of build-up tape under a standard grip. Many players actually prefer this feel, as it makes the grip feel just a bit more substantial in their hands without the need for extra tape wraps.

Scenario 2: Putting a .600" Grip on a .580" Shaft

Here, the opposite happens. The grip doesn't have to stretch as much to slide onto the smaller shaft. The result is a finished grip that is approximately -1/64" smaller than standard. So if you usually play a standard grip, they may end up feeling thin and uncomfortable and can even throw off your game.

How Grip Thickness Impacts Your Swing

Okay, so we can make the grip a little thicker or thinner. Why does that matter out on the course? A lot, actually. The size of your grip has a direct influence on how your hands work during the swing. It's the steering wheel for your shots.

• Grips That Are Too Thick: Large grips tend to quiet the hands and restrict their ability to release (or turn over) through impact. For a player who fights a bad hook or a pull, a thicker grip can sometimes help to slow down that overactive hand action and straighten out the ball flight. However, for a golfer with a standard swing, it can restrict your hands too much, which may cause you to leave the clubface open at impact, leading to weak blocks, pushes, or slices out to the right.
• Grips That Are Too Thin: A grip that feels too thin (or is too small for your hands) allows for more reactive hand action. This can encourage a faster release of the clubhead, which can sometimes help players who struggle with a slice or a fade. The danger here is that thin grips can lead to over-activity, causing you to turn the clubface over too quickly and resulting in pulls and hooks to the left.

It's a delicate balance, and the right grip core size is your first step towards finding it.

Step-by-Step Guide: How to Find Your Shaft's Butt Diameter

Knowing how to manipulate your grip size is great in principle, but in order to put it into practice, you need to know your starting point: what is the butt diameter of your own shafts? Here’s how to find it.

Method 1: The Easiest Way - Check the Shaft Label

The butt end of most modern golf shafts will have information printed directly onto it. It may be covered by the old grip or grip tape, so you may need to clean the shaft up a bit to see it.

• Steel Shafts: On steel shafts like True Temper and Project X, look for a series of numbers printed under the top layer of clear coat, usually on the bottom third of the shaft. One of those numbers will typically be a .580 or a .600, which indicates the butt diameter.
• Graphite Shafts: Graphite shafts, like those from Fujikura or Mitsubishi, often have this spec printed as a part of the main graphics below the grip area. They often clearly state it along with other specs like weight and torque. Look for a number near ".600" or ".610".

Method 2: When You Can't Find a Label - Use Calipers

If the label is gone or too worn to read, you can get a definitive measurement using a pair of digital calipers if you have them.

1. Zero them out: Ensure the calipers are "wiped" or "zeroed," so they read 0.000 before you measure.
2. Gently close them: Place the jaws of the caliper around the shaft at its butt end. Do not pinch or compress the shaft, especially a graphite one. Just allow the jaws to rest lightly against the surface.
3. Take your reading: The number displayed is the shaft's butt diameter in inches.

You can also take the club to your local golf shop, where they will almost certainly have calipers and can measure it for you in seconds.

Method 3: The "Good Guess" When All Else Fails

If you can't find a label and don't own calipers, you can make a highly reliable guess based on industry standards.

• For Standard Men's Clubs: For the vast majority of men's steel and graphite shafts, the default is a .600" butt diameter. If you are in doubt, assuming .600 is a very safe bet.
• For Ladies'/Senior/Junior Clubs: These shafts are designed to be lighter and softer to fit smaller, less strong players, and they typically have smaller butt diameters to accommodate smaller grips. Usually, you'll find .580" or even smaller.

This "guess" method isn't perfect, but it's a great starting point when you have no other information available.

Final Thoughts

By understanding the relationship between grip core size and shaft butt diameter, you transform from being a passive consumer to being an informed player who can customize the feel and performance of their clubs. This simple check can make a real difference in how consistent and confident you feel over the ball.

While technical specs like grip size are important for performance, connecting the dots between your equipment and what's happening on the course is how we truly get better. With Caddie AI, it's like having a coach who can help you find those answers whenever you need them. Are your shots going left? Is it your swing or your grips? With the app, you can get instant advice that's not just about mechanics, but also about how your equipment influences your ball flight, helping you get to the root of your issues faster.