The Pizza Geometry Conspiracy
Pizzerias rely on your inability to do math. A 12-inch pizza costs $12. An 18-inch pizza costs $20. The 12-inch feels cheaper, right? Wrong.
The Area Formula ($A = pi r^2$)
Pizza is a circle (usually). The area grows with the *square* of the radius. * 12-inch Pizza (r=6): $3.14 imes 36 approx 113$ sq inches. * 18-inch Pizza (r=9): $3.14 imes 81 approx 254$ sq inches.
The 18-inch pizza is more than double the size of the 12-inch, but not double the price. You are getting 2.2x the food for 1.6x the cost.
The Crust Nuance
Larger pizzas also have a better Topping-to-Crust ratio. Unless you are a crust enthusiast, the larger pie is geometrically superior in every metric.