What Are the Acceptable Diameters for Golf Balls?

Most golfers spend hours thinking about a ball's aerodynamics, dimple pattern, and spin rate, but almost no time on its most fundamental characteristic: its size. The diameter of a golf ball is one of the foundational rules of the game, a specific measurement that ensures fairness and influences how the ball performs from tee to green. This guide will walk you through the official rule, explain why that number is so important, and help you understand what it all means for your game.

The Official Ruling: A Very Specific Number

According to the Rules of Golf, as governed by the USGA and The R&A, a conforming golf ball must have a diameter of not less than 1.68 inches (42.67 mm). This is the universal standard for any round of golf where the rules are being followed, including tournaments, club competitions, and any round you plan to post for your handicap.

Notice the specific wording: not less than. This is a minimum size requirement. There is technically no maximum diameter for a golf ball, although practicality and the other rules (like the maximum weight of 1.62 ounces or 45.93 grams) effectively create a functional ceiling. In practice, all conforming balls sold by major manufacturers hover right around this 1.68-inch mark, with only minute variations due to the manufacturing process.

Who Sets These Rules?

• The USGA (United States Golf Association): This body governs golf in the United States and Mexico.
• The R&A (The Royal and Ancient Golf Club of St Andrews): This body, based in Scotland, governs the game for the rest of the world.

These two organizations work together to publish and maintain a unified "Rules of Golf," which encompasses everything from on-course etiquette to extremely thorough equipment stipulations. Their goal is to protect the game's traditions and ensure that success is determined by a player's skill, not by equipment that creates an unfair advantage.

Why 1.68 Inches is the Standard

It's easy to look at that number and imagine it was picked randomly, but the 1.68-inch rule acts as a point of balance for the game, affecting everything from how far the ball travels to how it behaves on the greens. To understand why, it helps to look at the historical debate between two sizes of balls: the smaller "British" ball and the larger "American" ball.

The Old Days: "British Small Ball" vs. "American Large Ball"

For much of the 20th century, golf was played with two different sizes of balls.

• The American Ball: This is the 1.68-inch ball we use today.
• The British Ball: This ball was slightly smaller, with a minimum diameter of only 1.62 inches.

Players could often choose which ball to use depending on the competition, course requirements, or even weather. The smaller British ball was often preferred by highly skilled players for a couple of reasons. Theoretically, its smaller shape created less aerodynamic drag, allowing it to cut through the air and wind more efficiently. Many players felt it was easier to "work" the ball, meaning shape shots like draws or fades on command.

So why did we end up with the larger ball?

The switch to a single, global standard was largely about clarity, fairness, and making the game more user-friendly, especially on the green.

How Diameter Influences Performance

The argument for the larger ball being the standard often centered on its effect on playability in the short game and putting.

• Off the fairway: A larger diameter means the ball has more surface area and settles differently on the grass. It sits up just a bit higher off the fairway compared to a smaller ball, giving you a cleaner, more confident hit during full swings. For many amateurs, this small difference makes it slightly easier to avoid scalding or "thin" golf shots.
• On the green: This is where the debate was most intense. A larger ball sits higher on the turf, meaning you strike it closer to its equator with the putter face. This encourages a truer roll and less bouncing off the face. However, the big drawback is evident when you stop to think about it: a larger ball has a harder time falling into the hole, which is a standard 4.25 inches in diameter. There is simply less room for error. This means putts may lip out more often than the smaller ball, which had more chances to drop in.

Ultimately, the governing bodies concluded consistency was paramount. In 1974, The R&A announced it was phasing out the small ball for official tournaments. By 1990, the 1.68-inch ball was finally the single, definitive standard across the entire golfing world, ending decades of debate.

Are All Modern Balls the Exact Same Diameter?

This is a common question. You know the rule is 1.68 inches, so does that mean a Titleist Pro V1 has the same exact diameter as a Callaway Chrome Soft or a Srixon Z-Star? The answer is mostly yes, but there are some slight nuances.

Manufacturers design equipment to push exactly to the limits of the rules. While they all target that 1.68-inch threshold, manufacturing processes naturally have very tiny margins of error - or tolerances. While one ball might measure 1.681 inches and another might measure 1.683 inches, these are differences so small they are impossible for a player to perceive or have any practical effect on performance for players at any level.

The major difference you need to be aware of is the distinction between conforming and non-conforming balls.

Understanding Conforming vs. Non-Conforming Balls

Any ball you find at a pro shop bearing the label of a mainstream brand like Titleist, TaylorMade, Callaway, Srixon, Bridgestone, or Wilson will be a "conforming" ball. That means it has been tested and approved by the USGA and R&A. You can find this information on the USGA and R&A Conforming Golf Balls List, which is periodically updated online.

Occasionally, you might come across "non-conforming" balls. These balls are often sold as novelty items or specifically marketed for extra distance advantages. They may achieve this by being lighter than the 1.68-inch minimum or by having characteristics that produce unusually low spin or high bounce effects beyond the rules' limits. While they can be fun for a casual round, they are not legal in competitions or for recording a score for your handicap. Using one in competition is essentially the same as cheating.

Your Focus Should Be Elsewhere

As a golfer, one point I cannot stress enough is that since every legal golf ball on the market is 1.68 inches in diameter, diameter is not a factor you need to think about when selecting your golf ball. The difference is negligible. Focusing your energy on understanding elements that actually have a tangible impact on how the ball performs in your game is a far better use of your time.

Forget the micromeasurements. Instead, think like a professional fitter and ask yourself these three questions when choosing a ball:

1. What Compression Rating fits my swing speed?

Compression refers to how much a ball deforms at the moment of impact. It is measured on a scale from roughly 30 to 110. Slower players (under 90 mph with a driver) typically benefit from lower compression balls. Low compression allows the ball to compress more easily, generating better energy transfer and distance for slower swingers. Players with speeds over 100 mph benefit from high-compression balls, which provide more power and control at the speeds they generate.

2. Will an Ionomer or Urethane cover suit my game better?

This might be the most important decision. The cover is the outermost layer of the ball and it dictates feel and spin control, especially with wedges and chipping shots.

• Ionomer covers (like Surlyn) are harder and much more durable. They tend to spin less, which can reduce sidespin off the tee, resulting in straighter drives for many recreational golfers. Their major advantage is durability and distance.
• Urethane covers are usually found on "tour" or premium balls and are softer, providing more spin for ultimate control, especially around the greens. The extra spin enables experienced players to hit precise "checking" shots and to stop their ball quickly on approach shots. The downside is they cost more and are considerably less robust, more prone to scuffs from wedge shots or cart path skips.

3. How important is "Feel" versus "Distance" to me?

This boils down to personal preference. Some players love the muted, almost sticky feel of a urethane ball whereas others prefer the audible "click" of an ionomer cover off their putter. Some may prefer the feeling of greater control with wedges over the confident rumble of more distance with a driver. There are no wrong answers here - the best approach is to get a sleeve of two or three different types of balls that suit your swing speed and try them out on the course, especially the putting green. Paying attention to how each performs in your short game will tell you almost everything you need to know.

Final Thoughts

The acceptable diameter for all conforming golf balls is a minimum of 1.68 inches. This global standard aims to simplify and harmonize the game, removing some outdated advantages that mainly affected performance around the green and ensuring a fair test for all players.

At the end of the day, knowing the rules is just one piece of the puzzle that is playing better golf. There are countless factors, from equipment specifications to on-course decisions, that can feel overwhelming. We understand that often these questions arise at inconvenient times. That’s why we created Caddie AR as your personal 24/7 golf expert in your pocket. Whether you have a question about a rule, want advice for a tricky lie, or are unsure of the best strategy on a challenging hole, we provide clear, expert-level tips in seconds. It's designed to take the guesswork out of golf for you so that you can play every shot with confidence and focus on what matters most: enjoying the game.