Used to compare the price and total size of pizzas at various sizes.
Enter the quantity, check the box if it is by the slice, enter the total diameter (for the whole pie if a single slice), and then the total price. It will then compute the area, the equivalent standard 16” pizza slices, and standard 16” pies, as well as the price per each of those.
This doesn't take into account the depth of the pizzas. I could have added a 3rd dimension, but the value doesn't scale the same way. Adding a square foot of area adds more of everything, adding another half inch of depth only adds bread. You may or may not like the deeper dish, but everyone should agree a pizza twice as deep isn't worth exactly twice another pizza. It's a similar story for toppings or for quality of pizza from different places.
For reference, a normal pizza is 16". The fast food pizza places call that an extra large, they call 14" a large, and 12" a medium.