According to this http://webcache.googleusercontent.com/search?q=cache:wUuam1HU-ggJ:order.papajohns.com/nutrition.html+&cd=3&hl=en&ct=clnk It's about 3000-4000 calories for a 16 inch pizza. I remember seeing a graph once of calories per unit area for pizza with time. It starts off pretty low for Italian style pizza - thin crust, not that thick toppings. The Italian pizza actually looked - at least to me - pretty good.  Then you move up to Chicago deep pan pizza. This was a major leap forward in calories per unit area. Still it doesn't stop there. Stuffed crusts, double layer toppings and so on all add to the energy density of pizza.  The graph was pretty much exponential with time. And the other strange thing is that by the time you get to a Pizza hut, deep pan, stuffed crust, double topping monstrosity it doesn't look anywhere near as appetising as the Italian pizza that started it all off. Of course it must look good to some people otherwise companies wouldn't sell it.  The genius of American capitalism!