Golf Ball Size: What Are the Minimum and Maximum?

Do the USGA and R&A, the two governing bodies that set the rules of golf, impose a minimum and maximum size for golf balls? Yes and no. There is a minimum size, but there is no maximum size.

Minimum Golf Ball Size: 1.68 Inches

All golf balls, in order to conform to the Rules of Golf, must be a minimum of 1.680 inches (42.67 millimeters) in diameter. That is written into the Rules of Golf by the R&A and USGA.

Any golf ball that measures smaller than 1.68 inches in diameter is non-conforming and cannot be played in any competition or any round of golf that is being played under the rules.

There was a time in golf's past when golf balls smaller than 1.68 inches in diameter were legal for play: The R&A's minimum size was once 1.62 inches, ever so slightly smaller than today's golf balls. See our article about the old "small ball" and "American ball" era for more about that.

Maximum Golf Ball Size: None

You might be surprised to hear that there is nothing in the rules about a maximum golf ball size. So long as a ball conforms to all the other standards set forth in the rules (such as a maximum weight of 1.62 ounces/45.93 grams), the golf ball can be as large as you can imagine. A golf ball the size of a beach ball? Legal, so long as it conforms to all other specifications in the rules. Of course, you'll have a hard time getting a ball that size into the hole!

But golf balls are sometimes made that are very slightly larger than the 1.68 minimum diameter. A very slightly larger ball can offer a higher "moment of inertia" than a standard ball (all other things being equal), which can slightly influence the ball to travel in a straighter trajectory. So if you see a golf ball marketed as "straighter" or a claim that one will "help reduce your slice," it's possible that ball is very slightly larger in diameter than the minimum.

But, even though there is no maximum golf ball size, the vast majority of balls on the market are manufactured right at that minimum diameter of 1.68 inches.

Related articles:

• What do the numbers on a golf ball mean?
• X-Out balls: What you need to know
• What are golf ball stamped 'Practice'?

Sources:
Royal and Ancient Golf Club of St. Andrews. The Rules of Equipment, Conformance of Balls, https://www.randa.org/en/roe/the-rules-of-equipment/part-4-conformance-of-balls.
United States Golf Association. The Rules of Equipment, Rule 4-1, https://www.usga.org/equipment-standards/equipment-rules-2019/equipment-rules/equipment-rules.html#!ruletype=er§ion=rule&partnum=4&rulenum=4.