This article is from the Table Tennis (Ping Pong) FAQ, by ttennis@bu.edu with numerous contributions by others.
3.1 The ball shall be spherical, with a diameter of 38 mm.
3.2 The ball shall weigh 2.5 grams.
3.3 The ball shall be made of celluloid or similar plastic material
and shall be white, yellow, or orange and matt.
3.4 The standard bounce required shall not be less than 23.5 cm (9 7/32
in) or more than 25.5 cm (10 3/8 in) when dropped from a height of
30.5 cm (12 in) on a specially designed steel block. These heights
are measured from the bottom of the ball.
3.4.1 The standard bounce required shall not be less than 22 cm (8 3/4
in) or more than 25 cm (9 3/4 in) when dropped from a height of
30.5 cm (12 in) on an approved table.
 
Continue to: