Golf balls: what the rules fix, and what the makers vary.

The ball standard

Part 4 of the Equipment Rules sets the limits every ball must meet:

The ball must also not differ substantially from the traditional form and make. Part 4 says only balls made entirely of elastomeric materials are considered traditional, though traces of other materials are allowed. Parts that move relative to each other, or that are not concentric, are not allowed, though a single concentric core up to 0.9 inch across is permitted under conditions. An embedded chip for identification is allowed if the ball meets every other requirement.

The overall distance test was introduced in 1976, and the R&A says it was updated in 1980, 2002 and 2004, with test speeds unchanged since 2004. The ODS limit is 317 yards with a 3-yard tolerance. A change to the test conditions was announced in December 2023 and its timing has since been revised: a 17 June 2026 notice from the R&A and USGA says there will be no change to the ODS until January 2030. That story has its own page, the ball testing change.

The size rule has history: Part 3 notes that the smaller 1.62-inch "British" ball was banned worldwide in 1990. Wikipedia adds that it had been allowed in R&A-governed events until then and gave a distance advantage, especially in wind.

How balls are built

Wikipedia classes modern balls as two-, three- or four-piece by their number of layers, and says most non-professional golfers use solid-core two-piece balls, a design Spalding developed after acquiring Jim Bartsch's patent in 1967. It describes the older wound ball as a core wound with rubber thread under a thin balata cover soft enough to be cut by a mishit, and says Surlyn (an ionomer resin DuPont introduced in the mid-1960s) and urethane blends replaced balata because they were more durable.

Equipment brand Lynx Golf describes the construction types this way. These are a maker's descriptions, not test results:

• Two-piece: a large rubber core under a cover, usually ionomer. Lynx says this gives low driver spin and high durability but less control around the green, and calls it a fit for beginners and higher handicaps.
• Three-piece: core, mantle and cover. Lynx says the mantle keeps the ball fast off the driver while adding feel and spin on irons and wedges. Covers may be ionomer or urethane.
• Four-piece: a second mantle, usually under a urethane cover, which Lynx says separates low driver spin from high wedge spin, for better players with consistent strike and enough speed. Lynx says some tour balls are five-piece.

On covers, Lynx says urethane tends to grip the grooves more and feel softer, while ionomer lasts longer and usually spins less.

Dimples and compression

Wikipedia says most modern balls have about 300 to 500 dimples, which cut drag by creating a turbulent boundary layer and a narrower wake, and add lift from backspin. There is no rules limit on the number of dimples. It describes compression as depending mainly on the hardness of the core: higher-compression balls feel firmer and lower-compression balls feel softer.

Ball fitting: makers disagree

Bridgestone says matching compression to swing speed gets the most distance from a ball, with faster swings needing higher compression, and it positions its own models for faster or slower swingers accordingly. It also says it pioneered ball fitting in 2006. Those are the manufacturer's claims. Not every maker agrees: GolfMagic reported a Titleist representative calling swing-speed matching nonsense and favouring fitting from the green back, but we could read that article only as a search summary and could not confirm its wording.

The playing rules (Rule 4.2)

Rule 4.2 of the 2023 Rules of Golf, in effect from 1 January 2023, covers how balls are used:

• Conforming ball. Every stroke must be made with a conforming ball, which you may get from anyone, including another player on the course.
• No altered balls. You must not play a ball whose performance you deliberately changed, for example by scuffing or heating it or applying a substance other than for cleaning. The penalty is disqualification. Part 3 says marking a ball with a felt-tip pen is not a breach, and Rule 6.3a encourages players to put an identification mark on their ball.
• Ball breaks into pieces. Under Rule 4.2b there is no penalty, the stroke does not count, and you replay from where it was made.
• Cut or cracked ball. Under Rule 4.2c you may lift a ball to check it only if you reasonably believe it was cut or cracked during the hole being played. Mark the spot first and do not clean it (except on the putting green). It may be replaced only if it is clearly cut or cracked; scratches, scrapes and damaged paint do not count.

The conforming ball list

The R&A keeps a Conforming Ball List of balls submitted within the last 12 months and ruled to conform. Manufacturers submit 24 samples of each model, and to stay on the list after 12 months they must submit fresh samples. The R&A and USGA also test balls at random and can remove a model if a problem is found. The list is updated on the first Wednesday of every month, and it describes each model's pole and seam markings so similar balls can be told apart.

A ball missing from the list may never have been submitted, may have been ruled non-conforming, or may have dropped off when its 12 months ran out. The R&A says an expired or unsubmitted ball should still be treated as conforming for non-elite play, but may not be used where the list condition is in force. Part 3 says that without that condition, a ball is presumed conforming unless there is strong evidence otherwise.

That condition is Model Local Rule G-3, which requires every ball used to be on the current list, with disqualification as the penalty. The R&A recommends it for professional and top amateur competitions, and other events may use it at the Committee's discretion. Model Local Rule G-4, the one ball rule, lets a Committee require one brand and model, as a single list entry, for the whole round; it is recommended only for competitions of highly skilled players. Both apply only when a Committee adopts them.

Nothing on this page says a particular ball conforms. Check the current Conforming Ball List, and the Terms of the Competition, before relying on a ball in an event.