What was the original diameter of the table tennis ball before the 2000 rule change?

The original standard table tennis ball had a diameter of 38 millimetres before the 2000 rule change.

The ITTF increased the specified ball diameter from 38 millimetres to 40 millimetres after the 2000 Olympic Games. The larger ball was intended to slow play slightly and make the ball easier for spectators and television audiences to follow.

The change affected speed and air resistance. A larger ball generally travels more slowly and reacts differently to spin, although racket technology, technique, and ball construction also influence the game.

Modern competition balls are 40 millimetres in diameter and weigh 2.7 grams. Players and fans sometimes call the older ball the “38 mm ball” and the modern one the “40 mm ball,” which helps distinguish equipment from different eras.