What Is The Diameter Of A Basketball

what is the diameter of a basketball
what is the diameter of a basketball

Basketball sizes vary depending on the age, gender, and level of play. Understanding the diameter of a basketball is crucial for players and enthusiasts alike. In this article, we will explore the different sizes of basketballs used in various leagues and age groups.

NBA and College Basketball Sizes

The official size of a basketball used by the NBA is 29.5 inches in circumference. This size is also used in men’s college and high school basketball leagues. Meanwhile, the WNBA utilizes a slightly smaller ball, measuring 28.5 inches in circumference. For international play, such as FIBA competitions, men use a ball called Molten GL7, which has a circumference of 30.7 inches. Women, on the other hand, use the Molten GL6, which has a circumference of 29 inches.

Basketball Sizes

Youth Basketball Sizes

The ball size for youth basketball varies according to age. Boys in middle school (ages 12-14) and all women and girls aged 12 and up use a ball with a circumference of 28.5 inches. For children between the ages of nine and 11, a ball size of 27.5 inches in circumference is recommended and is the most commonly used in youth basketball leagues. Boys and girls aged 4 to 8 use basketballs with sizes ranging from 22 to 24.5 inches in circumference, depending on their hand size.

Basketball Inflation and Pressure Regulations

Inflation and pressure regulations differ across leagues. In the NBA and WNBA, basketballs must be inflated to a pressure of 7.5 to 8.5 PSI. In the NCAA, the weight of the ball is regulated, with the men’s ball having a maximum weight of 22 ounces and the women’s ball having a maximum weight of 20 ounces. FIBA, on the other hand, specifies that the ball should be inflated to a specific air pressure and have a desired rebound height when dropped from a specified height.

Indoor vs. Outdoor Basketballs

When it comes to playing basketball, the type of basketball used depends on the environment. Indoor basketballs are made of full-grain leather, providing a smooth and firm grip. These balls are not suitable for outdoor use as the rough concrete surface can damage the leather and affect the ball’s grip. Some indoor basketballs are made of composite or synthetic leather, which eliminates the need for breaking in like regular leather balls but may not offer the same quality.

On the other hand, outdoor or “street” basketballs are made of rubber. Rubber balls are designed to withstand the rougher surface of concrete courts while maintaining a good grip. They are often recommended for beginners due to their ease of control.


Q: What is the diameter of an NBA basketball?
A: An NBA basketball has a diameter between 9.43 and 9.51 inches.

Q: What is the diameter of a WNBA basketball?
A: A WNBA basketball has a diameter between 9.07 and 9.23 inches.

Q: What is the diameter of a basketball in the NCAA?
A: In the NCAA, the diameter of a men’s basketball ranges from 9.39 to 9.55 inches, while the diameter of a women’s basketball ranges from 9.07 to 9.23 inches.


Understanding the diameter of a basketball is essential for players to choose the appropriate size for their age and level of play. From the NBA to youth leagues, basketball sizes can vary significantly. By knowing the sizes and regulations, players can ensure they are using the correct basketball for optimal performance. For more information on basketball and other fascinating topics, visit Top Q&A.

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