Find the recommended basketball size by age and format, with the 5-on-5 player-group split shown only when it affects the result.
How the Basketball Size By Age Calculator Works
The 5-on-5 table uses size 5 for ages 7-8 and size 6 for ages 9-11. From age 12, girls and women use size 6 while boys and men use size 7. USA Basketball's 3x3 guidance uses a junior or size 5 ball for ages 6-9 and a 3x3 ball with size 6 circumference from age 10.
Formula: 5-on-5: ages 7-8 = size 5, ages 9-11 = size 6, girls/women ages 12+ = size 6, boys/men ages 12+ = size 7; 3x3: ages 6-9 = junior/size 5, ages 10+ = 3x3/size 6 circumference
Choosing the Right Inputs
Choose format and age first. The girls/women or boys/men selector appears only for 5-on-5 players age 12 and older because it does not change the other recommendations. Check mode compares a current size with the selected standard.
| Format and players | Ball size | Circumference | Metric |
|---|---|---|---|
| 5-on-5, all ages 7-8 | Size 5 | 27.5 in | 69.9 cm |
| 5-on-5, all ages 9-11 | Size 6 | 28.5 in | 72.4 cm |
| 5-on-5, girls/women 12+ | Size 6 | 28.5 in | 72.4 cm |
| 5-on-5, boys/men 12+ | Size 7 | 29.5 in | 74.9 cm |
| 3x3, ages 6-9 | Junior or size 5 | 27.5 in | 69.9 cm |
| 3x3, ages 10+ | 3x3 or size 6 circumference | 28.5 in | 72.4 cm |
Understanding Your Results
The recommendation or equipment-check status appears first, followed by nominal circumference in both units, the applicable guideline users, and the current ball comparison when requested.
Worked Example
A 14-year-old boy uses size 7 in 5-on-5. The same player uses an official 3x3 ball with size 6 circumference in 3x3, which is why the format choice matters.
Assumptions and Limitations
Leagues may use different cutoffs or equipment. Official 3x3 balls combine size 6 circumference with their own mass specification; this calculator focuses on size and circumference only.
Sources
NBA and USA Basketball. Youth Basketball Guidelines, Rules and Standards, 2018.
USA Basketball. 3x3 Rules Page, Equipment and Dimensions, 2026.
