Most players in grades 3 to 5 use a size 5 basketball (27.5 inches). Girls in middle school and up use a size 6 (28.5 inches). Boys move to a size 7 (29.5 inches) in 7th or 8th grade or in high school, depending on the league. Players in grades K to 2 use a size 4 (25.5 inches). The right size helps players build good shooting form. This guide from Pro Skills Basketball (PSB) coaches breaks it down by size, age and grade.
PSB partner deals: PSB earns a small commission when you shop through these links or use code PROSKILLS-15, at no extra cost to you.
Key Takeaways
- Size 5 (27.5 inch) is the most common youth size, for grades 3 to 5
- Size 6 (28.5 inch) is the official size for girls and women, from middle school to the WNBA
- Size 7 (29.5 inch) is the official size for boys high school, college and the NBA
- Boys switch from size 6 to size 7 at different grades depending on the league
- Too big a ball builds bad shooting habits
What are the basketball sizes?
Basketballs come in five common sizes. The size number is a label for the circumference, the distance around the ball.
| Ball size | Circumference | Weight | Who usually uses it |
|---|---|---|---|
| Size 7 | 29.5 inches | About 22 oz | Boys in high school and up, men’s college and the NBA. Many boys leagues switch to size 7 in 7th or 8th grade. |
| Size 6 | 28.5 inches | About 20 oz | Girls in middle school and up, women’s high school, college and the WNBA, and boys around ages 12 to 14 in many leagues. |
| Size 5 | 27.5 inches | About 17 oz | Boys and girls in grades 3 to 5, about ages 9 to 11. The most common youth size. |
| Size 4 | 25.5 inches | About 14 oz | Players in grades K to 2, about ages 5 to 8. |
| Size 3 | 22 inches | About 10 oz | Mini ball for the youngest players and for ball handling drills. |
Brands label their balls by age in different ways. Wilson’s guide lists size 7 for men ages 12 and up, size 6 for men and women ages 9 and up, and size 5 for ages 8 and under. Leagues set their own rules, so check yours.
What size basketball should my player use by grade?
Most youth leagues follow this pattern. Always check your league’s rulebook, since boys leagues move to size 7 at different grades.
| Grade | Girls | Boys |
|---|---|---|
| K to 2nd | Size 4 | Size 4 |
| 3rd to 5th | Size 5 | Size 5 |
| 6th | Size 6 | Size 6 |
| 7th to 8th | Size 6 | Size 6 or 7 (check your league) |
| 9th to 12th | Size 6 | Size 7 |
Why does the right size matter?
A ball that fits lets a player shoot with one hand under the ball and the guide hand on the side. A ball that is too big or too heavy makes young players push the ball from the chest, and that habit is hard to unlearn later.
The right size also builds confidence. Players who make shots keep practicing. That is why youth leagues use smaller balls and, often, lower rims for the youngest players.
Should I buy an indoor or outdoor ball?
Buy the ball for where your player trains most. Indoor balls have a soft composite or leather cover that grips well on gym floors but wears out fast on concrete. Outdoor balls have a tougher rubber or composite cover built for driveways and parks. Indoor/outdoor balls sit in between.
Many players own two: an indoor game ball like the Wilson Evolution and an outdoor ball for daily reps at home.
How do I check that a ball fits?
- Your player can hold the ball out with one hand under it, without it rolling off.
- They can shoot from the free throw line with good form, not pushing from the chest.
- They can dribble below the waist with control.
If a ball fails these tests, drop down a size for practice at home.
Shop the right size
- Wilson size 7 basketballs (29.5 inch)
- Wilson size 6 basketballs (28.5 inch)
- Wilson size 5 basketballs (27.5 inch)
- Wilson mini basketballs (size 3)
Frequently Asked Questions
What size basketball should a 10 year old use?
Most 10 year olds use a size 5 basketball, which is 27.5 inches around. It is the standard ball for grades 3 to 5 in most youth leagues.
What size basketball do middle school girls use?
Middle school girls use a size 6 basketball, 28.5 inches around. Girls keep using size 6 through high school, college and the WNBA.
What size basketball do middle school boys use?
It depends on the league. Many 6th grade boys use a size 6 (28.5 inch) ball, and many leagues move boys to a size 7 (29.5 inch) in 7th or 8th grade. Check your league or school rules.
Is a size 7 basketball the official size?
Yes. Size 7 (29.5 inches) is the official ball for boys high school, men’s college and the NBA. Size 6 (28.5 inches) is the official ball for girls and women’s basketball, including the WNBA.
Should my player practice with a bigger ball?
No. Young players build better shooting form with a ball that fits their hands and strength. A ball that is too big or heavy leads to pushing shots and bad habits.
Is there a discount on Wilson basketballs?
Yes. PSB families and fans can use code PROSKILLS-15 for 15% off Wilson basketballs at wilson.com, including custom balls.
Ready to put the new ball to work? Build a free workout with our workout builder, or find a PSB clinic or camp near you.
By Brendan Winters, Co-Founder and Chief Growth Officer
Brendan co-founded Pro Skills Basketball in 2009 and is its Chief Growth Officer. At Davidson College he was a two-time All-American and Southern Conference Player of the Year. He then played five pro seasons in France, Germany, Hungary and Greece.
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