Basketball Sizes by Age: What Size Should Your Kid Use?
The Quick Answer
Basketball sizes go by number. The smaller the number, the smaller the ball. From Under 12s up we follow the Basketball NSW (BNSW) guidelines which are used across all BNSW competitions, from local leagues to state-level programs. For the youngest kids, Size 3 (ages 4–5) and Size 4 (ages 6–7) sit below the comp pathway but they’re the right starting points developmentally.
Here’s what your child needs based on their age:
| Age | Boys | Girls |
|---|---|---|
| 4–5 | Size 3 | Size 3 |
| 6–7 | Size 4 | Size 4 |
| 8–11 | Size 5 | Size 5 |
| 12–13 | Size 6 | Size 6 |
| 14–15 | Size 6 | Size 6 |
| 16+ | Size 7 | Size 6 |
The simple version: Size 3 for ages 4–5. Size 4 for ages 6–7. Size 5 for ages 8–11. Size 6 from age 12. Boys move to Size 7 from age 16.
In 2023, Basketball NSW officially introduced the Size 5 ball for all Under 12 competitions, including the Spalding Waratah League, Skills Days and High Performance programs. The change came after research with other states (Basketball Victoria made the same move in 2022) showing that a correctly sized ball helps younger players develop better shooting and ball handling technique.
As BNSW’s General Manager of Coaching & Development Brett Coxsedge put it: “The introduction of the size 5 ball will allow a focus on better shooting and ball handling skills for our junior players. This will allow younger players and beginners to hone and perfect their skills at an early age.”
Sizes by Comp Age Group
Some of you think in comp age groups rather than birthdays. Same guide, the way BNSW runs it:
| Comp age group | Boys | Girls |
|---|---|---|
| U8 / U10 / U12 | Size 5 | Size 5 |
| U14 | Size 6 | Size 6 |
| U16 | Size 7 | Size 6 |
| U18 and seniors | Size 7 | Size 6 |
The youngest kids sit below the comp pathway on a Size 3 (ages 4–5) or Size 4 (ages 6–7). If your kid plays school or social comp rather than BNSW, go by the age table above and check what ball their comp uses. When they’re playing up an age group, they use the comp’s ball in games. For the driveway, buy by age.
It’s a Guide, Not a Law
Every age range here is a guide.
If your kid is showing solid control, technique and ability with the smaller ball and they’re “big enough”, move them up. Some kids are ready early.
But here’s the rule of thumb I’ve landed on after years of coaching: when in doubt, keep them on the smaller ball. Long term it builds finger dexterity, touch and control that a bigger ball can’t. A kid who has mastered the small ball moves up easily. A kid who jumped up too early fights the ball for years.
Why Size Matters
A ball that’s too big or too heavy makes everything harder. Dribbling feels awkward. Shooting means heaving it at the ring. They can’t develop proper form because they’re fighting the ball the whole time.
The right size ball sits comfortably in their hands. They can control it. They can shoot with proper technique instead of just launching it. That’s where real skill development happens.
I see it all the time. A kid shows up with a full-size ball (Size 7) and wonders why they can’t dribble properly. We swap it out for the right size and suddenly everything clicks. There’s a reason BNSW made the change.
Indoor, Outdoor or Indoor/Outdoor?
Before we get into the sizes, this is the other call you’ve got to make. There are three types of basketball:
- Indoor balls (leather or composite leather) are designed for wooden indoor courts only. Take one out on concrete and it’ll get chewed up fast. This is not your everyday ball.
- Outdoor balls (rubber) are designed for the driveway and outdoor courts but they’ll work fine indoors too. Tougher, less grip, very forgiving.
- Indoor/outdoor balls (composite leather) are the middle ground. Decent feel, decent durability, happy on both surfaces.
For everyday use, an outdoor or indoor/outdoor ball is the right call. Kids bounce balls in the driveway, bring them to indoor sessions, take them to school. You want one ball that can handle the lot.
The indoor ball as a milestone
Indoor balls are a different thing. They’re not the everyday ball. They’re the special one.
When a kid is really loving the game, a fresh indoor ball is a moment. It’s crisp. It’s soft. It’s exclusive. The way it feels in your hands, the way it sounds bouncing off a wooden floor. Kids notice. It’s the same kind of moment as buying your first pair of proper basketball shoes — a sign that this thing they love is being taken seriously.
Save the indoor ball for when they’re committed and putting in the work. Drop it as a present and watch what happens. They’ll guard it like gold and only break it out for indoor sessions. A big moment for a kid who loves basketball.
So the call: outdoor or indoor/outdoor for the everyday ball. The indoor ball comes later.
Size 3 — Ages 4–5
Size 3 isn’t part of the BNSW competition pathway (formal comp starts at Under 12 with Size 5) but for the littlest kids who are just learning to bounce a ball, it makes a real difference.
It’s the lightest and easiest to grip. Four and five year olds don’t have the hand strength for anything bigger yet. You’ll see them slapping at the ball, struggling to two-hand dribble or heaving wild shots that have no chance. Size 3 lets them actually develop coordination and proper form instead of fighting the ball.
If your kid is 4 or 5, that’s the size to grab.
Size 4 — Ages 6–7
By 6 most kids have the hand strength to step up to a Size 4. Still small, still light, but there’s enough ball there to start building real dribbling and shooting habits.
If your kid is 6 or 7, grab the Size 4 and let them own it. No rush to the Size 5.
Size 5 — Ages 8–11
This is the BNSW standard for all Under 12 players, boys and girls. It’s noticeably smaller and lighter than what you’d see in an adult game. That’s the point.
At this age kids are still developing hand strength and coordination. A Size 5 lets them actually grip the ball and work on their skills without everything being a struggle. It’s the same ball they’ll use in any BNSW junior competition, so they’ll be training with what they play with.
Grab them a Size 5 and they’re set.
Size 6 — Ages 12 and Up
Size 6 is the official women’s game ball and the BNSW standard for girls from Under 14s onwards. For boys, Size 6 is the Under 14s ball before they step up to Size 7 at Under 16s.
Most kids are ready for this transition around age 12. If your child is 11 and already strong with a Size 5, there’s no rush to move up early. Let them build confidence and technique first. That’s the whole reason BNSW extended the Size 5 to Under 12s.
Size 7 — Boys 16 and Up
Size 7 is the men’s game ball, used in BNSW competitions from Under 16 boys onwards. It’s the ball boys will use through senior competitions and representative basketball.
For girls, Size 6 is the game ball at every level from Under 14s up. Even if she’s tall for her age or plays in mixed competitions, Size 6 is the standard.
Where to Buy
You don’t need to spend a fortune. A solid kids’ ball is $25–$50. Spalding, Molten and Wilson all make good ones in the right sizes.
Two easy places to shop:
- Rebel Sport — basketballs — biggest range, you can filter by size and brand. Most of what you want will be here.
- Kmart — basketball — cheaper option if you just need a starter ball.
Quick checklist before you click buy:
- Right size — Size 3 for ages 4–5, Size 4 for ages 6–7, Size 5 for ages 8–11, Size 6 from age 12 (BNSW standard from Under 12s up)
- Outdoor or indoor/outdoor — handles the driveway and the school court (skip indoor-only unless it’s a milestone gift)
- Decent grip — they should be able to hold it comfortably in one hand (or two for younger kids)
- Properly inflated — a flat ball kills development. Grab a cheap pump if you don’t have one
The Driveway Test
Not sure if the ball is right? Watch them dribble in the driveway.
- If they’re slapping at it and can barely keep it going, the ball might be too big or too heavy.
- If it looks like a tennis ball in their hands, they’re probably ready to size up.
- If they can dribble comfortably at waist height with some control, that’s the right fit.
FAQ: Sizes by Age
What size basketball for a 4 or 5 year old?
Size 3. It sits below the comp pathway but little hands need it. They’ll actually be able to dribble and shoot with proper form instead of fighting the ball.
What size basketball for a 6 or 7 year old?
Size 4. Still small and light, but enough ball to start building real dribbling and shooting habits before the step up to Size 5 at 8.
What size basketball for an 8 or 9 year old?
Size 5. It’s the Basketball NSW standard for every player under 12, boys and girls, so they’ll practise with the same ball they play with.
What size basketball for a 10 or 11 year old?
Still Size 5. There’s no prize for sizing up early. Let them get strong and confident with the 5 before the jump to Size 6 at 12.
What size basketball for a 12 or 13 year old?
Size 6 for boys and girls. Most kids are ready for the move around age 12.
What size basketball do girls use?
Size 6 from age 12 at every level, right up to the pros. Girls never move to the Size 7.
When should my kid move up a ball size?
When they’re showing solid control, technique and ability with their current ball and they’re big enough. When in doubt, keep them on the smaller ball. Long term it builds finger dexterity, touch and control a bigger ball can’t.
What is a youth size basketball?
That label usually means a Size 5. Ignore the label and check the number printed on the ball: 3 for ages 4 and 5, 4 for ages 6 and 7, 5 for ages 8 to 11, 6 from age 12.
Bring Whatever You’ve Got
Here’s the thing. Don’t let the ball stop you from getting started. If your child has a ball at home, bring it. We can figure out sizing at the session. I’d rather they show up with the wrong ball than not show up at all because you weren’t sure what to buy.
At Inner Game we’ve got spare balls at every session, but not endless ones. The best way to make sure your kid always has a ball in their hands is to grab them their own and bring it to class. It’s their ball, so the reps don’t stop when the session does. Now you know what to look for.
Want to put that new ball to use? Have a look at our weekly basketball training classes in Sydney, private 1-on-1 coaching or school holiday camps, or book a free trial and bring the ball along.
Related reading: What age should my child start basketball?