Did you know that until 1990, the R&A and USGA, golf's governing bodies, could not agree on the size of the golf ball? There were two different sizes of golf balls in use around the world, with a very slightly smaller version of the ball available for play in areas governed by R&A rules.

The minimum size of golfs balls was not standardized in the Rules of Golf until 1990. And the size agreed up then remains in place today. The current rule on minimum golf ball size is:

Golf ball diameter in inches: 1.68

Golf ball diameter in centimeters: 4.2672

Golf ball diameter in millimeters: 42.672

The 'British Ball' and 'American Ball'

For most of the history of the Rules of Golf, the sport's two governing bodies disagreed about the minimum size of golf balls:

R&A's minimum golf ball diameter: 1.62 inches

USGA's minimum golf ball diameter: 1.68 inches.

(The two governing bodies always agreed that the weight of a golf ball should be 1.62 ounces.)

The R&A approved golf balls with minimum diameters of 1.62 inches in the early 1900s. But in the early 1930s, the USGA ruled against those smaller balls, sticking with a minimum diameter of 1.68 inches.

The oh-so-slightly larger ball played in USGA-governed areas became known as the "American ball," while the smaller ball golfers in R&A areas had the option to use was known as the "small ball," "British ball" or "British Open ball." (And for good measure, it was occasionally called the "European ball.")

"British ball" or "British Open ball" was the term for it most commonly used by American golfers and fans because those golfers typically only encountered the ball during the Open Championship. To golfers playing under R&A rules, it was simply the "small ball."

(Note that the golf ball sizes above are minimums; golf balls could be, and can be, larger than the minimums mentioned in the Rules of Golf. So R&A golfers always had the option to play the larger American ball if they wished.)

American Pros Preferred the Small Ball at the Open

The smaller ball was an option for golfers playing under R&A rules; it was not an option for golfers playing under USGA rules.

But American pro golfers almost unanimously preferred the smaller ball when playing in the British Open. Arnold Palmer, Jack Nicklaus and most other American golfers switched to the British ball when they played the Open Championship (or any other competition governed by R&A rules).

Why? A 0.06-inch difference in golf ball diameter doesn't sound like much. But according to golfers who played the two different golf balls back then, the smaller ball provided a bit more distance and was more workable in the wind.

Golf Ball Size Finally Standardized in 1990

Over the years, a desire grew to standardize the rules on golf ball size. The difference in minimum golf ball diameter was one of the last major disagreements between the R&A and USGA that was codified in the rules.

The R&A took the first step in 1974, when it decided the small ball could no longer be used in the British Open. That meant that golf's major championships, at least, were all played with the same size golf balls from 1974 onward.

But it took all the way until the 1990 update to the Rules of Golf before the R&A and USGA settled on one, single approved, minimum size for golf balls, and it was the USGA's: 1.68-inches in diameter. And that relegated the "small ball" or "British ball" to history.