Footballs come in several sizes to accommodate athletes of different ages. Younger athletes use smaller balls, and football sizes gradually increase as athletes advance to higher levels
"We have different football sizes because it would be very difficult for a 9- or 10-year-old kid to throw an NFL ball," explains Kevin Krysiak, Director of Global Innovation Team Sports at Wilson, the primary supplier of footballs to the NFL and NCAA. "The different sizes were created to be appropriate for athletes at each level."
The governing bodies at each level determine the football's dimensions, and manufacturers like Wilson must adhere to their guidelines. Although players may use different-sized balls throughout their career, that doesn't necessarily mean they're using different balls. Krysiak says that Wilson prides itself in offering a consistent experience throughout its product line.
Below are the dimensions of footballs from the NFL to Junior level.
http://www.stack.com/a/football-sizes
NFL- Length: 11 inches
- Width: 7 inches
- Diameter: 21 inches
Collegiate/High School- Length: 11 inches
- Width: 7 inches
- Diameter: 21 inches
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Youth (12-14 years old)- Length: 11 inches
- Width: 6.5 inches
- Diameter: 19.5 inches
Junior (9-12 years old)- Length: 10.5 inches
- Width: 6 inches
- Diameter: 18.5 inches
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