Basketball sizes vary by age, gender, and level of play. The official size of the basketball used by the NBA is 29.5 inches in circumference, which is the same size used throughout men’s college and high school basketball leagues. The WNBA uses a slightly smaller ball, measuring 28.5 inches in circumference. For international play, the basketball used is what’s called a Molten GL7 for men and Molten GL6 for women, which are slightly bigger than the NBA ball, with a 30.7-inch circumference for the men’s ball and a 29-inch circumference for the women’s.

Below is a summary of the different basketball sizes:

• Size 7: 29.5” in circumference and has a standard weight of 22 oz. This is the standard ball size for men’s professional basketball associations, such as the NBA, as well as men’s college, high school, and travel basketball leagues.

• Size 6: 28.5” in circumference and has a standard weight of 20 oz. This ball is slightly smaller than size 7 basketballs, making them ideal for players with smaller hand spans. This is the official ball size for most women’s professional basketball associations, including the WNBA and International Basketball Federation (FIBA) 3x3, in addition to women’s college and high school basketball leagues, and in youth leagues for players 12 and up.

• Size 5: 27.5”-27.75” in circumference and has a standard weight of 14-16 oz. This is the most popular basketball size for youth leagues and is ideal for players 8 and under.

• Size 4: 25.5” in circumference and has a weight of only 14 oz. These child-friendly basketballs are ideal for children 6 and under.

It is important to choose the right-sized ball for your level of play, as playing with an incorrectly sized ball can have long-term negative effects on a player’s technique.