How many sizes of soccer balls are there?
FIFA officially recognizes five soccer ball sizes:
- Size 1: Measures 18 - 20 inches, but can sometimes vary
- Size 2: Measures 20 - 22 inches, used to practice ball control
- Size 3: Measures 23 - 24 inches, "Junior" 
- SIze 4: Measures 25 - 26 inches, "Youth"
- Size 5: Measures 27 - 28 inches, "Standard"
FIFA regulations also dictate that balls be inflated between 8.5 and 15.6 psi.