World Aquatics rules set men's match-ball circumference at 68–71 cm and women's at 65–67 cm; both weigh 400–450 g. Match caps need same-color malleable ear protectors and a chin fastener, while starting goalkeepers wear red cap number 1. Check the event's current rulebook for age-group, national and alternate-format requirements.
Match equipment is set by the event rules, not just the number printed on a ball. Under the current World Aquatics regulations, men’s and women’s matches use different ball circumferences, while weight stays in the same range. Cap color, ear protection and numbering also matter for team equipment.
Match-ball dimensions
| Match category | World Aquatics ball specification |
|---|---|
| Men’s | 68–71 cm circumference; 7.5–8.5 psi; 400–450 g |
| Women’s | 65–67 cm circumference; 6.5–7.5 psi; 400–450 g |
The regulations also specify a round, waterproof ball with a self-closing valve. Ask the coach or event organizer which match category applies before ordering: a manufacturer’s size label alone does not show whether the ball matches your competition’s current rulebook.
What to check on a match cap
- Ear protection: World Aquatics requires malleable ear protectors in the same color as the rest of the cap.
- Secure fit: The cap fastens under the chin and is worn while players are on the field of play and specified substitution areas.
- Team distinction: Field players on opposing teams need caps that are easy to distinguish. Goalkeepers wear red.
- Numbers: Starting goalkeepers wear number 1; field players wear numbers 2–14. The regulations allow number 15 for a third goalkeeper at certain events with rosters of 15 or more.
If you are comparing a general-purpose cap for lap swimming, start with our silicone, latex and Lycra cap guide. For separate earplug fit and use, see swim earplugs and nose clips; earplugs do not replace a water polo cap’s required ear protectors.
Check the competition, then buy
Use the current rules for the event you will play. World Aquatics regulations cover its competitions, while USA Water Polo publishes national playing rules and event documents. Age-group tournaments and alternate formats can have their own equipment directions, so confirm the ball category and cap details with the team or event before buying.
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Common questions
What size ball is used in water polo?
World Aquatics rules set men's match balls at 68–71 cm circumference and women's at 65–67 cm. Local and age-group events may use different specifications.
What number does a water polo goalkeeper wear?
The starting goalkeeper wears red cap number 1 under World Aquatics rules. Field players wear numbers 2–14, and substitute goalkeepers may use numbers 2–14.
Do water polo caps need ear guards?
Yes. World Aquatics requires malleable ear protectors that match the cap color, with the cap fastened under the chin.
Are water polo ball sizes the same for every age group?
No. The dimensions here come from current World Aquatics match rules; youth leagues and national event formats can set different equipment requirements.