What is the diameter of a tennis ball?

The official diameter of a tennis ball according to the International Tennis Federation must be between 2.575 and 2.7 inches. Tennis balls are sold in cylinders containing three per package.

Tennis as known today was developed during the 1870s from a game referred to as yard tennis. This game has been around from centuries, but the modern game was developed in England during this time. The tennis balls were typically made out of leather and rubber, and white and black in color. The yellow balls known today were patented in 1972. The idea behind requiring the yellow balls was it was more visible on television to viewers.