Pizza value: compare area, not just diameter
Work through two pizza offers using area and price per equal area, with clear limits for crust, thickness and toppings.
Method
Diameter is a length, but a round pizza covers an area. Comparing diameters alone understates how much the size changes. Keep diameter units and currency consistent, and enter the total price for the entire offer rather than mixing single-pizza and bundle prices.
Circle area is pi times the square of the radius. Since radius is half the diameter, doubling diameter multiplies area by four. A diameter increase from 30 cm to 40 cm multiplies one pizza’s area by 16/9, or about 1.7778, rather than by 4/3.
Now compare a bundle of two 30 cm pizzas with one 40 cm pizza. The bundle has area 450 pi cm², while the larger single pizza has 400 pi cm². The bundle therefore contains 12.5% more circular area. Counting pizzas alone does not establish which offer is larger.
View data
- 2 × 30 cm
- 1413.716694 cm² 450π cm²
- 1 × 40 cm
- 1256.637061 cm² 400π cm²
Worked example
Now compare a bundle of two 30 cm pizzas with one 40 cm pizza. The bundle has area 450 pi cm², while the larger single pizza has 400 pi cm². The bundle therefore contains 12.5% more circular area. Counting pizzas alone does not establish which offer is larger.
If the two-pizza bundle costs 24 and the single costs 22 in the same currency, their prices per 100 cm² are approximately 1.69765 and 1.75070. Under this area-only comparison, the bundle is about 3.03% cheaper per equal area. Use unrounded areas during the division.
circle area = π × (diameter / 2)²
two 30 cm pizzas = 450π ≈ 1413.716694 cm²
one 40 cm pizza = 400π ≈ 1256.637061 cm²
price per 100 cm² = total price × 100 / total area
Area is one comparison, not a complete measure of value or a serving recommendation. Crust width, dough thickness, toppings, cooking style and preferences can change the decision. The illustrated slices explain circular geometry; they do not prescribe portion sizes or imply that every pizza is cut the same way.
View data
- Pizza diameter (cm)
- 30 cm
- Number of pizzas
- 2
- Total price
- 24
Checks and limits
Area is one comparison, not a complete measure of value or a serving recommendation. Crust width, dough thickness, toppings, cooking style and preferences can change the decision. The illustrated slices explain circular geometry; they do not prescribe portion sizes or imply that every pizza is cut the same way.