Golf grips come in two standard sizes -- .580 and .600 inches -- which refer to the size of the diameter in the open end of the grip, also called the core. Because players have different preferences for what feels right in a golf grip, clubmakers have created options by switching grip sizes and adjusting the wraps of grip tape between the grip and the shaft.
The standard grip sizes are M58, which has a core diameter of .580 inches, and M60, which is .600 inches in diameter in the core. These are standard because most shafts have a diameter of .580 and .600 inches. Putting an M58 grip on a .580 shaft, therefore, creates a standard-size grip.
M58 grips have the same outside diameter as M60 grips, which means the material of the M58 grip must be .02 inches thicker to achieve the smaller core diameter.
Golfers have different size hands, and grips come in five sizes -- junior, undersize, standard, midsize and jumbo. A player may fit between sizes, so a club fitter can mismatch grips and shafts to accommodate the player. For example, a midsize grip has an outside diameter of 1/16 of an inch larger than standard, but installing an M58 grip on a .600-inch shaft produces a total diameter that is 1/32 of an inch larger than standard.
Grips can be stretched lengthwise 3/4 of an inch before installation to make them thinner. Stretching is equivalent to taking away one layer of build-up tape. Each wrap of build-up tape equals 1/64 of an inch in overall diameter.
Advanced players pay more attention to the feel of a club. Some players may want a thicker-feeling grip and less tape. Others may like more build-up tape under the grip. That means that the first player would prefer an M58 grip on a .600-inch shaft with no build-up tape for an overall grip diameter of .920 inches and the other player would prefer an M60 grip on the same shaft with one wrap of build-up tape for the same overall diameter.