Water Polo Ball Size Guide

Choosing the right water polo ball size is essential for proper skill development, fair competition, and player safety. In water polo, ball sizes range from Size 1 (Splashball) for young beginners to Size 5 (Men's) for high school boys, college men, and international competition. Each size is matched to specific age groups and competition levels based on guidelines from USA Water Polo and World Aquatics (formerly FINA).

This guide from the SwimOutlet team covers every ball size, complete specifications, and tips for choosing and maintaining your water polo ball.

Water Polo Ball Size Chart

Note: Sizes 1, 2, and 3 do not have official World Aquatics specifications for circumference, weight, or pressure. Measurements for these youth sizes vary by manufacturer. Sizes 4 and 5 have strict regulated specifications enforced for all sanctioned competition.

Size 1: Splashball

• Most commonly used in introductory water polo camps where boys and girls aged 8 & under try out water polo for the first time.
• The small size makes it easier for young, beginning players to handle, catch, and pass the ball with one hand.
• Sometimes called a "mini-trainer" — ideal for recreational pool games and splash polo programs.

Size 2: Junior

• Used by 12 & under girls and 10 & under co-ed players.
• The smaller size is appropriate for this age range as young players learn fundamental water polo skills like passing, catching, and shooting.
• Approved by World Aquatics as the official size for junior play.

Size 3: Intermediate

• Used by 14 & under girls and 12 & under boys.
• This transitional ball is designed and volumetrically engineered to provide a smooth progression to the Size 4 ball, improve skill development, and increase quality of play at the youth level.
• Commonly used in training sessions and youth leagues as the stepping stone to regulation-size competition balls.

Size 4: Compact (Women's)

• Used by 14 & under boys; 16 & under girls club; 18 & under girls club; all high school girls; NCAA women; and International women (including the Olympics).
• Regulated circumference: 65–67 cm (25.6"–26.4")
• Weight: 400–450 grams (14–16 ounces)
• Inflation pressure: 12–13 psi (83–90 kPa)
• The Size 4 ball is the official competition ball for all women's water polo from high school through the Olympics.

Size 5: Men's

• Used by 16 & under boys club; 18 & under boys club; all high school boys; NCAA men; and International men (including the Olympics).
• Regulated circumference: 68–71 cm (26.8"–28.0")
• Weight: 400–450 grams (14–16 ounces)
• Inflation pressure: 13–14 psi (90–97 kPa)
• The Size 5 ball is the largest water polo ball and the official competition ball for all men's water polo from 16U club through the Olympics.

What Are Water Polo Balls Made Of?

Water polo balls are made from waterproof rubber or rubberized nylon with a textured surface designed for grip in wet conditions. The textured covering creates a tacky feel when wet, allowing players to hold, pass, and shoot the ball with one hand despite its large size — a necessity since players are treading water and cannot use the pool bottom for leverage.

Inside the ball is an inflatable rubber bladder similar to those found in soccer balls and basketballs. The combination of the waterproof exterior and inflatable bladder allows the ball to float on the water surface.

Ball Color Regulations

Standard water polo balls are yellow, adopted in 1948 for maximum visibility in the water (replacing the original red). Modern regulations from NFHS and NCAA require competition balls to be yellow with black lines, though colored panels (blue, green, red, or black middle stripes) are now permitted in sanctioned games. The yellow color ensures the ball stands out clearly against the blue-green water for players, referees, and spectators.

Heavy Trainer / Weighted Water Polo Balls

In addition to standard game balls, weighted training balls (sometimes called heavy trainers) are available for strength and conditioning work. These balls are typically double the weight of a standard ball — around 800 grams to 1 kilogram (1.75–2.2 lbs) — and come in Size 4 and Size 5. Weighted balls are used during practice to build arm, shoulder, and core strength for shooting and passing. They should not be used in games or scrimmages.

How to Inflate and Care for Your Water Polo Ball

Proper inflation and maintenance keep your water polo ball performing correctly and lasting longer:

• Always wet the inflation needle before inserting it into the valve — a dry needle can damage the valve seal.
• Use a standard hand pump or bicycle pump with a ball needle attachment. Electric inflators also work well for teams inflating multiple balls.
• Inflate to the correct PSI: 12–13 psi for Size 4 (women's) and 13–14 psi for Size 5 (men's). No official standards exist for smaller sizes, so use your judgment — the ball should feel firm but not rock-hard.
• Check inflation regularly — water polo balls deflate gradually from constant impact during play. A poorly inflated ball affects shooting accuracy, passing distance, and training quality.
• Rinse after every use with fresh water to remove chlorine, salt, or debris.
• Store in a cool, dry place out of direct sunlight. UV exposure and heat degrade the rubber covering over time.
• Avoid sitting or standing on the ball — this can deform the shape and damage the bladder.

How to Choose the Right Water Polo Ball

1. Check your age group and competition level — use the size chart above to determine the correct ball size for your league, club, or school team.
2. Match the ball to the league's color requirements — some leagues require specific color combinations (yellow/navy, yellow/black, etc.). Practice balls can be any color.
3. Consider grip texture — different manufacturers (KAP7, Mikasa, Turbo) use different grip patterns. Try to test a few brands to find the texture that feels best in wet conditions.
4. Buy a weighted trainer if you're focused on building throwing strength — use the same size as your game ball (Size 4 or 5).

Shop All Water Polo Balls →

Essential Water Polo Gear

In addition to the right ball, make sure you have the rest of your water polo kit:

• Water polo caps — Numbered caps with ear guards for team identification and ear protection.
• Water polo suits — Durable suits designed to withstand the physical demands of the sport.
• Water polo goals — Regulation and practice goals for training and competition.
• Swim goggles — For practice sessions (goggles are not worn during competition). See our goggles guide.

FAQs

What size water polo ball do I need?

It depends on age and gender. Boys 14 and older and all men use Size 5. Girls 14 and older and all women use Size 4. Boys 12 and under and girls 14 and under use Size 3. Girls 12 and under and co-ed 10 and under use Size 2. Kids 8 and under use Size 1 (Splashball). Always check with your league for specific requirements.

How much does a water polo ball weigh?

Both Size 4 (women's) and Size 5 (men's) regulation water polo balls weigh between 400 and 450 grams (14–16 ounces). The weight is the same across both sizes — the difference is circumference, not mass. Sizes 1–3 do not have official weight standards and are generally lighter.

What PSI should a water polo ball be inflated to?

Size 4 (women's/compact) balls should be inflated to 12–13 psi (83–90 kPa). Size 5 (men's) balls should be inflated to 13–14 psi (90–97 kPa). There are no official PSI standards for sizes 1–3. Always wet the inflation needle before inserting it into the valve to avoid damaging the seal.

What is the difference between Size 4 and Size 5 water polo balls?

The main difference is circumference. Size 5 (men's) has a circumference of 68–71 cm, while Size 4 (women's/compact) has a circumference of 65–67 cm. Both sizes weigh the same (400–450 grams), but the Size 5 ball is inflated to slightly higher pressure (13–14 psi vs. 12–13 psi). The larger circumference of the Size 5 is proportional to the generally larger hand size of male players.

Why are water polo balls yellow?

Yellow was adopted in 1948 to replace the original red color for better visibility in the water. The bright yellow stands out clearly against the blue-green surface of the pool, making it easier for players, referees, and spectators to track the ball. Modern regulations now also allow colored panels (blue, green, red, or black stripes) alongside the yellow.

Are water polo balls the same as volleyballs?

No. While they may look similar in size, water polo balls are specifically designed for wet conditions with a textured, tacky rubber surface that provides grip when wet. Volleyballs have a smooth leather or synthetic cover that becomes slippery in water. Water polo balls also feature waterproof construction that allows them to float, whereas volleyballs absorb water and become heavy. Never substitute one for the other.

This guide is written and maintained by the SwimOutlet swim team. Ball specifications are based on current USA Water Polo and World Aquatics (formerly FINA) regulations. For more water polo resources, browse our complete water polo collection and our pool dimensions guide for water polo pool specs.