What Is the Size of a Golf Ball?

A golf ball feels like such a simple object, but its size is governed by incredibly specific rules that have a massive impact on the game. These regulations, set by the USGA and R&A, standardize play and dictate everything from how far you can hit the ball to how it behaves on the green. This guide will walk you through the official dimensions of a golf ball, the surprising history behind the standard, and how these subtle specs translate to your performance on the course.

The Official Dimensions: What the Rulebook Says

When it comes to conforming golf balls for any kind of official play, from a Saturday morning competition to the U.S. Open, the rules are straightforward and apply universally. The guidelines aren't about creating one single, identical ball, but rather setting boundaries that manufacturers must operate within. All conforming balls must pass rigorous testing to ensure they meet these standards.

The Numbers You Need to Know

The two most important measurements you need to know are the golf ball's diameter (size) and weight. The official Rules of Golf state:

• Diameter: The diameter of the ball must not be less than 1.68 inches (42.67 mm).notice there's no maximum size here, only a minimum. In theory, a manufacturer could make a larger ball, but it would have more air resistance and wouldn't travel as far, making it commercially non-viable. So, for all practical purposes, every conforming golf ball is made to be as close to this 1.68-inch minimum as possible.
• Weight: The weight of the ball must not be greater than 1.62 ounces (45.93 g). This is a maximum limit. A heavier ball could potentially cut through wind better and carry more momentum, giving players an undue advantage. Manufacturers generally aim to get as close to this maximum weight as they can without going over.

Beyond these two core specs, the rules also require a ball to be "spherically symmetrical." This means it's designed to fly in a consistent, predictable way regardless of how it's oriented on the tee. The dimple pattern and any markings must be evenly distributed to prevent the ball from having a "heavy" or "light" side that affects its flight.

A Tale of Two Golf Balls: How We Got to 1.68 Inches

For a large part of golf's modern history, not every golfer played with the same size ball. For decades, the game was split by an Atlantic divide, creating two very different playing experiences.

The "American" Ball vs. the "British" Ball

In the United States, the USGA mandated the 1.68-inch ball (often called the "larger ball" or "American ball") as their standard early on. However, across the pond, the R&A, which governs golf for the rest of the world, permitted the use of a smaller ball that had a minimum diameter of just 1.62 inches. This "small ball," also known as the "British ball," had a huge impact on strategy and play.

What were the differences in performance?

• The Small Ball (1.62 inches): Players felt the smaller ball was easier to launch high and that it cut through the wind more effectively, giving it a potential distance advantage. Its smaller size, however, was a disadvantage around the greens. It had a tendency to sink deeper into the rough or poor lies, making recovery shots more difficult. Many professional players also found it trickier to putt with, feeling it was "fidgety" on the green surface.
• The Large Ball (1.68 inches): The American-sized ball sat up better on pretty much any lie, from pristine fairways to fluffy rough, inspiring more confidence at address. Players also felt it was more stable on the putting surface and easier to control on delicate chips and pitches around the green.

This difference was a point of contention for decades, especially during The Open Championship, where American players would often switch to the "small ball" for the week to gain a perceived advantage in the British coastal winds. Greats like Jack Nicklaus and Arnold Palmer were known to make the switch. Finally, in 1990, the R&A officially adopted the 1.68-inch standard, unifying the rules worldwide and ending the era of the small ball in professional golf.

It’s Not Just Size: What Really Makes a Golf Ball Fly

While the 1.68-inch standard is fundamental, it's the features on the ball's surface that truly dictate its performance through the air. The biggest factor here is the dimple pattern.

The Power of Dimples

Have you ever tried to throw a completely smooth, perfectly round ball? It moves erratically and won't go nearly as far as one with texture. The same physics applies to a golf ball. A smooth golf ball hit with a driver might only travel half the distance of a modern dimpled ball.

Here's how it works in a simple way:

1. As a ball flies, it creates a pocket of low-pressure air, or "wake," directly behind it. This wake produces significant drag, acting like a parachute slowing the ball down.
2. The dimples on a golf ball create a very thin layer of turbulent air that "clings" to the ball's surface.
3. This turbulent layer helps the air flow more smoothly around the back of the ball, drastically reducing the size of that wake.

The result is less drag and more lift. This combination allows a golf ball to travel much farther and with a more stable trajectory. While the R&A and USGA have rules about symmetrical design, they do not regulate the number, shape, or depth of dimples. This is where manufacturers like Titleist, Callaway, and TaylorMade spend millions in research and development, constantly refining their aerodynamic designs. Most modern golf balls have between 300 and 450 dimples, each pattern designed to optimize flight characteristics for different types of shots.

Playing Outside the Rules: The World of Non-Conforming Balls

Because the rules set a minimum size and maximum weight, it opens the door for so-called "non-conforming" or "illegal" golf balls. These balls are designed purely for recreational fun and cannot be used in handicap-scoring rounds or any official tournament.

Why would a ball be non-conforming?

• It's too small: Some illegal balls are made undersized, reducing drag for more distance.
• It's too heavy: Others are made heavier than the 1.62-ounce limit, helping them carry extra momentum.
• It's too "hot": The most common type of illegal ball has a core and cover construction that makes it rebound off the clubface faster than the limit allows. This creates significantly more initial velocity and, therefore, more distance.

These balls are often marketed towards senior golfers, beginners who want an extra boost, or for charity scramble tournaments where the goal is simply to have a fun day. There's nothing wrong with using them outside of official competition, but just know they fall outside the standardized rules of the game.

From the Rulebook to the Fairway: What This Means for You

As a coach, a common question I get is, "What golf ball should I play?" Since the size and weight are standardized for all conforming balls, you don't really have to worry about that aspect. Your choice should come down to the other features that manufacturers use to differentiate their products.

So, instead of a ball's size, here are the three things you should actually focus on when choosing the right ball for your game:

1. Construction (Number of Layers)

A golf ball is built in layers, and each layer adds a different performance characteristic.

• 2-Piece Balls: These have a large core and a cover. They are designed for distance and durability. They typically have lower spin, which means they are great off the tee for reducing hooks and slices but offer less stopping power on approach shots.
• 3-Piece Balls: These add a mantle layer between the core and cover. This layer helps provide a balance of distance off the tee and soft feel/spin around the greens. It's an excellent all-around choice for a wide range of golfers.
• 4 and 5-Piece Balls: Often called "tour balls," these have multiple mantle layers that are fine-tuned to react differently to different clubs. They offer low spin with the driver for distance and high spin with wedges for maximum control - the best of both worlds, but they come at a premium price.

2. Cover Material (Urethane vs. Ionomer)

The cover of the golf ball has the biggest influence on feel and greenside spin.

• Ionomer (like Surlyn): A durable material found on most 2-piece and some 3-piece balls. It's firm, feels "clicky" off the club, and produces less spin, promoting more roll-out on drives and chips.
• Urethane: A softer, premium material found on most 3-piece and all tour-level balls. It provides a soft feel and "grabs" the grooves of your wedges and short irons, creating significantly more spin for shots that stop quickly on the green.

3. Compression

Compression is a measure of how much a golf ball "squishes" at impact. Lower numbers are for slower swing speeds, while higher numbers are for faster swing speeds. A slower swinger needs a lower compression ball to activate the core and maximize distance. A faster swinger benefits from a higher compression ball for better control and energy transfer.

Don't get lost in the weeds. A simple rule of thumb: If you need distance and durability, look for a 2-piece ionomer-cover ball. If you want more feel and stopping power around the greens, try a 3-piece (or more) ball with a urethane cover.

Final Thoughts

As we've seen, the official size of a golf ball is the result of a long history of design and regulation, unified today at a minimum of 1.68 inches in diameter. This standard ensures a fair and predictable foundation for the game, allowing the real differences to shine through in a ball's dimple design, construction, and materials.

Knowing the specs is helpful, but what truly matters is translating that knowledge into smart decisions on the course. While I can't be there for every shot, our Caddie AI acts as your personal coach in your pocket. Instead of guessing how to play a tricky shot from a bad lie in the rough, you can get instant, expert advice. It removes the uncertainty, helping you make the confident, smart play that lowers your scores and makes the game that much more enjoyable.