At least you didn’t measure the pizzas with your feet.

On this episode of: The internet goes to primary school

yeah, but
C_1 = pi * d = 3,14 * 18 = 56,52
C_2 = pi * d * 2 = 3,14 * 12 * 2 = 75,36

so the smaller ones have 50% more crust and are therefor more delicious.

What’s an inch?

If you let the radius be Z, then you can find the area of a pizza with a simple formula:

Pi * Z * Z = A