For instance, the area of an eight-inch pizza is about 50 square inches. Compare that to a 16-inch pizza, which on first glance you might assume is twice as big. In reality, a 16-inch pizza has over 200 square inches of pizza. That's four times as much pizza, and it's certainly not coming at four times the price.
ASAP Science goes a step further, using pricing research done by NPR's Planet Money in 2014. A 20-inch pizza on average cost $20.77 in 2014. It has more area than two 14-inch pizzas, which would cost $29.59 on average. A 20-inch pizza also has more area than six eight-inch pizzas, which costs $51.56 on average. Math says you need more pizza.