Size Duel deck / Sport and everyday things
Tennis ball
Length: diameter (rules allow 6.54–6.86 cm)
about 67 mm (2.64 in)
Range used for fair duels: 65.4 mm to 68.6 mm.
Rules fix the size within a third of a centimetre.
Sources and checks
Checked 2026-10-19: Claude (AI build agent): Wikidata statement compared, second-source quote verified in the fetched page. Quotes are short passages from each source.
Wikidata P2386: 6.7 centimetreQ246514, CC0, retrieved 2026-10-19
“6.54-6.86 cm (2.57-2.70 inches)”ITF Technical Booklet 2023 (Rules of Tennis, Appendix I): source, retrieved 2026-10-19, read with a web fetch
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