Pizza is round because spinning the dough in the air naturally stretches it into a circle.

Spinning pizza dough uses centrifugal force. This is the same force that pulls you toward the outside of a spinning carnival ride. As the dough rotates, the force pushes the mass away from the center. This stretching makes the dough thinner and wider without the baker having to pull it by hand.Researchers at the University of L'Aquila studied this motion in 2013. They found that spinning keeps the dough stable and prevents it from tearing. A round shape is also the most efficient for heat. In a traditional oven heated to 800 or 900 degrees Fahrenheit, heat moves evenly toward the center of a circle.The Associazione Verace Pizza Napoletana was formed in 1984 to protect traditional pizza rules. They state a real Neapolitan pizza must be round and no larger than 35 centimeters across. This specific size and shape ensure the crust stays moist while the toppings cook. Cutting a circle into wedges also ensures every slice has an equal amount of crust and toppings.