Basketballs come in six standard sizes, from a size 1 mini up to the size 7.
A size 7 basketball is 29.5 inches around and weighs 22 ounces, and it’s the official ball for men’s high school, college, and professional basketball.
A size 6 (28.5 inches, 20 ounces) is the official ball for women at every level, and everything below that is sized for kids by age.
The right size depends on the player’s age and gender. Get it wrong and you’re not just making the game harder… you’re teaching bad habits that stick.
Below you’ll find the full basketball sizes chart, what each size is used for, the official sizes by league, and exactly which size to use at every age.
Basketball Sizes Chart by Age
(Chart scrolls left and right on mobile)
The size number is the industry standard. Sizes 7, 6, and 5 are the three you’ll find in most stores, and they’re the only three used in organized competition. Sizes 4 and below are for skill development and play.
Basketball Sizes Explained
Here’s what each size is, who it’s built for, and where it’s used.
Size 7 Basketball:
Circumference: 29.5 inches (75 cm)
Weight: 22 ounces (620 g)
Diameter: About 9.4 inches
Used by: Men and boys 14 and older
The size 7 basketball is the official ball for men’s basketball at every level. The NBA, men’s college basketball, and boys’ high school basketball all use it.
This is what most people mean when they say “full size” or “regulation” basketball.
For boys, I recommend moving to a size 7 at 14 years old. Some manufacturers say 15, some say 12 or 13. More on that debate below.
Size 6 Basketball
Circumference: 28.5 inches (72 cm)
Weight: 20 ounces (570 g)
Diameter: About 9.1 inches
Used by: Women and girls 12 and older. Boys 12 to 13.
The size 6 basketball is the official ball for women’s basketball at every level. The WNBA, women’s college basketball, and girls’ high school basketball all use a 28.5-inch ball.
It’s also the right ball for boys in their first two years of middle school before they move up to a size 7.
Because girls and women never move past a size 6, it’s often called the “women’s ball” or “intermediate ball” in stores.
Size 5 Basketball
Circumference: 27.5 inches (70 cm)
Weight: 17 ounces (480 g)
Diameter: About 8.75 inches
Used by: Boys and girls 9 to 11
The size 5 basketball is the standard youth ball. It’s the one most kids use when they start playing organized basketball and learning the rules of the game.
This is the size a lot of youth leagues get wrong.
Plenty of 9 to 11 year olds are handed a size 6 (or worse, a size 7) because it’s what the gym has in the ball rack.
If your league runs 9–11 year olds on a size 6, it’s worth asking why.
Size 4 Basketball
Circumference: 25.5 inches (65 cm)
Weight: 14 ounces (400 g)
Diameter: About 8.1 inches
Used by: Boys and girls 5 to 8
The size 4 basketball is for kids who are just starting out. At this age they’re not playing rule-based games, so the ball only needs to do one thing:
Be small enough and light enough for a 6-year-old to shoot with proper form.
A size 4 is 8 ounces lighter than a size 7. That’s the difference between a kid getting the ball to the rim and a kid throwing it from their hip with two hands.
Size 3 Basketball
Circumference: 22 inches (56 cm)
Weight: 10 ounces (280 g)
Diameter: About 7 inches
Used by: Ages 4 to 7
The size 3 basketball is the “mini” ball. It’s perfect for young kids getting comfortable holding, bouncing, and throwing a basketball for the first time.
It’s also the ball you’ll see sold as a souvenir at NBA games, which tells you how seriously it’s taken as a game ball. But for a 4-year-old, it’s the right tool.
Size 1 Basketball
Circumference: 16 inches (41 cm)
Weight: 8 ounces (230 g)
Used by: Ages 2 to 4
The size 1 is the “micro-mini.” It’s a toy, and that’s fine. It exists so toddlers can get a ball in their hands before they’re big enough for anything else.
Official Basketball Size by League
The official basketball size for every major league comes down to two balls:
Size 7 for men and size 6 for women.
1. NBA – Size 7. 29.5 inches in circumference, 22 ounces. Inflated to between 7.5 and 8.5 psi.
2. WNBA – Size 6. 28.5 inches in circumference, 20 ounces. Same inflation range as the NBA.
3. NCAA (College) – Size 7 for men (maximum 30 inches, 22 ounces). Size 6 for women (maximum 29 inches, 20 ounces). The college rulebook sets maximums rather than exact numbers, which is why you’ll see slightly different figures quoted.
4. High School (NFHS) – Same as college and the pros. Size 7 for boys, size 6 for girls.
5. FIBA (International) – Also size 7 for men and size 6 for women, but FIBA’s specs run slightly larger. A FIBA men’s ball can measure up to 30.7 inches (78 cm) and a women’s ball up to 29 inches (74 cm). It’s why NBA players sometimes comment that the Olympic ball feels a touch bigger.
If you’re buying a ball for a competitive team, check which rulebook your league uses. For most youth and high school programs in the US, that’s NFHS, and the sizes above apply.
What Size Basketball by Age
Here’s the recommendation I’ve been giving coaches and parents for years:
1. Ages 2–4 – Size 1 or size 3. Whatever they can hold.
2. Ages 5–8 – Size 4. Rim at 8 feet.
3. Ages 9–11 – Size 5. Rim at 9 feet.
4. Ages 12–13 (boys) – Size 6. Rim at 10 feet.
5. Ages 12+ (girls) – Size 6. Rim at 10 feet.
6. Ages 14+ (boys) – Size 7. Rim at 10 feet.
Why the charts don’t agree
If you’ve looked at more than one basketball sizes chart, you’ll have noticed they contradict each other.
Spalding says boys can use a size 7 from 13. Adidas says 15. Wilson says 12. USA Basketball’s youth guidelines allow a size 7 for boys as young as 12.
Here’s the thing:
Manufacturers are describing what sells, not what develops players. Coaches see the results of kids shooting a ball that’s too heavy for them, and we consistently want players on the smaller ball for longer.
The governing bodies are slowly catching up. In 2021, Basketball Victoria moved every under-12 competition in the state from a size 6 to a size 5 after a review by its high performance coaches. Basketball NSW followed in 2023.
That’s exactly in line with the chart above. When in doubt, go smaller for longer.
Why the Right Basketball Size Matters
Ask me the easiest change we could make to improve youth basketball and I’ll give you the same answer every time:
Make sure every age group is playing with the correct-sized basketball.
Yet in gyms all over the world we have 6-year-olds playing with the same ball as NBA players. I’ve watched full games of under-8s on a size 7 where most of the kids couldn’t get the ball to the height of the rim.
There are three reasons it matters so much:
1. Shooting Technique – A size 7 weighs more than twice as much as a size 3. To get a ball that heavy to the rim, a young player has to cheat. They drop the shoulder, twist the hips, push with two hands, or “chuck” it from the chest. Practice those habits for two or three seasons and they’re brutal to fix once the player is old enough to shoot properly. The right size ball lets kids learn to shoot the correct way from the start.
2. Ball Handling and Passing – A ball that’s too big for a player’s hands can’t be controlled with the fingertips. Dribbling becomes slapping, and passes lose their snap. Kids on the right size ball learn to dribble and pass with proper hand position because the ball actually fits.
3. Enjoyment – If you’re an adult, imagine trying to shoot with a bowling ball. That’s roughly what a size 7 feels like to a 5-year-old. Kids on a ball they can handle make more shots, complete more passes, and have more success early. The more success they have in their first few years, the more likely they are to stick with the game.
Basketball Sizes FAQ
Is a 28.5 basketball a size 6 or a size 7?
A 28.5-inch basketball is a size 6. A size 7 is 29.5 inches. The one-inch difference doesn’t sound like much, but the size 6 is also two ounces lighter, and you can feel it.
Should I get a size 6 or size 7 basketball?
If the ball is for a boy 14 or older or an adult man, get a size 7. If it’s for a girl or woman 12 or older, or a boy aged 12 to 13, get a size 6. If you’re an adult playing casual pickup in a mixed group, a size 7 is the safer buy because that’s what everyone else will have.
What size basketball for a 14-year-old boy?
Size 7. This is the age I recommend boys move up to the full-size ball. If your son is 14 but small for his age, there’s no harm in another season on a size 6 as long as his league allows it.
At what age do boys start using a full-size basketball?
Boys should move to a size 7 (full size) at 14, when they’re entering high school. Some leagues and manufacturers allow it from 12 or 13. In my experience that’s too early for most boys, and the extra year or two on a size 6 pays off in shooting form.
How big is a basketball in inches and cm?
A full-size (size 7) basketball is 29.5 inches around, which is 75 cm. Its diameter is about 9.4 inches (24 cm). A women’s size 6 ball is 28.5 inches (72 cm) around with a diameter of about 9.1 inches. Youth balls run from 27.5 inches down to 16 inches.
What pressure should a basketball be inflated to?
Most basketballs should be inflated to between 7.5 and 8.5 psi, which is the range the NBA and WNBA use. The recommended pressure is usually printed next to the valve. A simple check: drop the ball from about shoulder height and it should bounce back to roughly hip height.
Conclusion
Basketball sizes exist for a reason. A size 7 is the right ball for a grown man and the wrong ball for a 7-year-old, and pretending otherwise is how kids end up with shooting habits they carry for life.
Use the chart. Keep young players on the smaller ball for longer. And if your league hasn’t looked at basketball sizes in a while, ask them to.
It’s the easiest fix in youth basketball.
