well it depends... usually it will say the size and what age it's good for on the box. but it depends on your age
A Size 7 basketball is usually 29.5 incheshttp://www.hrsinformer.com/2009/10/how-to-choose-a-basketball/
No, 28.5 is a women's size basketball. For a men's size basketball, it should say official size and weight.
It should fit.
So a size 7 basketball is a men's size basketball. A size 6 basketball is a woman's size basketball. That means a size 5 is for people who have smaller hands. That's how you compare sizes.
The typical size basketball used for middle school basketball games is a size 6 basketball.
A size 28.5 would do just fine. but make sure that its as full as it will go or as bouncy as you want it.
If your a TRUE basketball player, you should automatically be able to tell if it is a 29.5 (size 7) basketball, BUT, if not, you can ask the person in the store, or it should say size 7 somewhere on the ball.
The Official Basketball Hoop size is 21 inches
basketball
The regulation size of a basketball used in 7th grade basketball games is typically size 6, which has a circumference of 28.5 inches.
The regulation size of a basketball used in middle school basketball games is typically size 6, which has a circumference of 28.5 inches.
Middle school basketball typically uses a size 6 basketball.