One big pizza, or two smaller ones?
Pizza area grows with the square of the diameter, not the diameter itself — so a single bigger pie is very often more food than two smaller ones whose sizes sound like more when you just add them up. An 18-inch pizza alone beats two 12-inch pizzas combined, even though 12 + 12 = 24 sounds huge next to 18.
One big pizza d₁
A ∝ d₁²
8 indiameter24 in
Two smaller pizzas d₂
A ∝ 2×d₂²
Total area
sq in — one big
sq in — two smaller, combined
Try
Circle area is A = πr² (area of a circle), where r is half the diameter you set above. Because area scales with the square of diameter, doubling a pizza's diameter roughly quadruples how much you get to eat — which is also why comparing pizza deals by price-per-inch-of-diameter is misleading, and price per square inch is the fair way to do it. This page is pure geometry: it doesn't model a real pizzeria's crust-to-topping ratio, how thin the dough is stretched at larger sizes, or that a chain's "18-inch" isn't always exactly 18 inches edge to edge.