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How big is a Basketball?

24 centimeters!

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Basketball

A basketball is the ball used to play basketball, and a standard one is about 24 centimeters (9.4 inches) across. That standard ball, called a size 7, is used in men's games and weighs about 600 grams (1.3 pounds). Women's and children's games use slightly smaller balls.

Size

Basketball's rules describe a ball by its circumference, the distance around it, rather than by its width. FIBA, the international basketball federation, requires a size 7 ball to measure 750–770 millimeters around and to weigh 580–620 grams. Dividing the circumference by pi (about 3.14) gives the width: 23.9–24.5 centimeters.

Women's games use a size 6 ball, 715–730 millimeters around and about 23 centimeters across. Mini-basketball, for young children, uses a size 5, about 22 centimeters across. College basketball in the United States sets limits close to size 7: 29.5–30 inches (749–762 millimeters) around.

Size comparisons

  • The ring of a basketball hoop is about 45 centimeters (18 inches) across on the inside, a little less than twice the width of the ball.
  • A basketball is about four-fifths the length of a 12-inch (30-centimeter) ruler.
  • A person 1.7 meters (5 feet 7 inches) tall is about as tall as seven basketballs stacked on top of each other.
  • If Earth were shrunk to the size of a basketball, the Moon would be about the size of a tennis ball, orbiting about 7 meters (24 feet) away.
  • About 53 million basketballs lined up side by side would stretch across Earth.

How a ball is checked

A ball also has to be inflated to the right pressure, and FIBA checks this with a bounce test. Dropped onto the floor from about 1.8 meters, measured from the bottom of the ball, it must bounce back to between 1,035 and 1,085 millimeters. A ball that bounces higher is overinflated, and one that bounces lower is underinflated. Every ball is marked with its size number and the pressure it should be pumped to.

How the game began

James Naismith invented basketball in the winter of 1891–1892. He was teaching at the International YMCA Training School, now Springfield College, in Springfield, Massachusetts. The first games were played with a soccer ball. For goals, Naismith asked the school's janitor for two boxes about 18 inches (46 centimeters) square, and was given two peach baskets instead.

Naismith nailed the baskets to the lower rail of the gym's balcony, which happened to be 10 feet high. The rules still set that height: FIBA and the NBA both place the top of the ring 3.05 meters (10 feet) above the floor.

Sources

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