Tennis ball
67 mm (2.638 in)
Diameter
A regulation ball for professional tennis. Diameter: about 6.7 cm.
Published
How big is that?
67 mm is 78% of a credit card.
Tennis ball is the 10th smallest of the 39 Classic objects, and the 10th smallest of the 109 objects across all three SizeItUp games.
Closest in size from the other games: Archaeopteryx (Prehistoric Giants), 50 cm long.
Size comparison
To scale, smallest to largest: Tennis ball in orange beside the Classic objects nearest in size, in teal.
| Object | Size | vs Tennis ball |
|---|---|---|
| AA batteryThe common cylindrical battery in remotes and toys. | 50.5 mm long | 75% of the size |
| Rubik's Cube (3 x 3)The original six-color twisty puzzle. | 57 mm | 85% of the size |
| Tennis ball | 67 mm across | – |
| BaseballAn official Major League Baseball ball, red stitches and all. | 73.8 mm across | 1.1× bigger |
| Credit card (ID-1 size)A standard bank card, the same size as most ID and loyalty cards. | 85.6 mm | 1.3× bigger |
In other units
| Millimetres | 67 |
|---|---|
| Centimetres | 6.7 |
| Metres | 0.067 |
| Inches | 2.638 |
| Feet | 0.2198 |
How it's measured
Diameter. Midpoint of the ITF range 6.54-6.86 cm (Type 1, 2 and high-altitude balls).
The source gives a range, so this is the middle of it.
Sources
- itftennis.com: ITF Rules of Tennis 2026, Appendix I: size 6.54-6.86 cm.
Checked against the source on .
Could you have guessed it by eye?
Tennis ball is one of the objects in Classic, a daily size comparison game: you stretch a shape to the size you think is right beside one you know.