Pizza Size Calculator
Compare pizza sizes by actual surface area — two 12-inch pizzas vs one 18-inch is not the obvious answer. Quick math for ordering and value comparison.
Last updated: May 2026
Enter two diameters to compare surface area.
Why pizza size matters more than you think
Pizza area scales with the square of the radius, not the diameter — so a small increase in diameter has a large effect on total food. A 40 cm pizza has π × 20² = 1,257 cm². Two 28 cm pizzas total 2 — π × 14² = 1,232 cm². The single large pizza has more area than two mediums, even though 40 is less than 56. This is why the large pizza is almost always better value per euro.
Adding 5 cm to a 30 cm pizza (to 35 cm) increases area by 36%. Adding the same 5 cm to a 20 cm pizza increases area by 56%. The effect of diameter is non-linear — which is the entire point of this calculator.
Frequently Asked Questions
Is a large pizza better value than two smalls?
Almost always yes. A 40 cm pizza has 1,257 cm² of area. Two 28 cm pizzas together total 1,232 cm² — slightly less than a single 40 cm. The large pizza wins on area and typically costs less per cm². The exception is when the smaller pizzas have different toppings, which changes the comparison to preference rather than area.
Why does diameter matter more than people expect?
Area = π × radius². Radius is half the diameter, so doubling the diameter quadruples the area. A 5 cm increase on a 30 cm base adds 36% more surface. Most people estimate pizza size linearly (bigger diameter = proportionally more food), which underestimates the actual difference by a large margin.
What is a 12-inch or 14-inch pizza in centimetres?
12 inches = 30.5 cm; 14 inches = 35.6 cm; 16 inches = 40.6 cm. Enter the converted value directly in centimetres. A 12" pizza has about 730 cm² of area; a 14" has about 995 cm² — 36% more for a modest-looking 2-inch difference in diameter.