Pizza Size Calculator

Pizza Size Calculator: calculate pizza size for cooking and nutrition. Practical tips and worked examples.

A pizza size calculator computes the actual area of a pizza from its diameter using the circle area formula (A = πr²), then compares two sizes by price per square inch to reveal which is the better value. The most common misconception about pizza sizes is that a 16-inch pizza is 33% bigger than a 12-inch pizza because the diameter is 33% larger. In reality, because area scales with the square of the radius, a 16-inch pizza has 78% more pizza than a 12-inch — nearly double. Recipe Scale Calculator covers related geometry calculations.

The value comparison feature divides the price by the area in square inches to give a price per square inch for each size. This makes it immediately clear which size offers more pizza per pound or dollar spent. Larger pizzas almost always have a lower price per square inch than smaller pizzas from the same restaurant, because fixed costs (labour, dough prep, oven time) are similar regardless of size.

Select "Compare two sizes" mode and enter the diameter of each pizza in inches.
Enter the price of each pizza.
The calculator shows the area of each pizza in square inches, the percentage difference in area, and the price per square inch for each.
The "Better value" row identifies which size gives more pizza per unit of currency.
Switch to "Single pizza" mode to see just the area and area per slice for one size.
Adjust the number of slices to compute area per slice for your preferred cut.

Pizza area and value formulas

Pizza area = π × (diameter ÷ 2)² — area scales with the square of radius, not diameter.

Price per square inch = price ÷ area

Area per slice = total area ÷ number of slices

Worked example: 12-inch pizza at £9.99 vs 16-inch at £13.99. Area of 12" = π × 6² = 113.1 sq in. Area of 16" = π × 8² = 201.1 sq in. Extra pizza by area = (201.1 − 113.1) ÷ 113.1 = 78% more. Price per sq in: 12" = £9.99 ÷ 113.1 = £0.0884; 16" = £13.99 ÷ 201.1 = £0.0696. The 16" is 21% cheaper per square inch despite costing £4 more.

Reading your pizza size result

Standard pizza sizes quick reference

Standard pizza diameters and their areas: 9-inch personal = 63.6 sq in; 10-inch small = 78.5 sq in; 12-inch medium = 113.1 sq in; 14-inch large = 153.9 sq in; 16-inch extra large = 201.1 sq in; 18-inch party = 254.5 sq in. A 16-inch pizza contains 78% more pizza than a 12-inch, not 33% as the diameter ratio suggests. Two 12-inch pizzas (226 sq in combined) are slightly larger than one 18-inch pizza (254 sq in) but usually cost more — check the price per square inch to confirm.

Food tips and best practices

Always compare by area, not by diameter — a pizza that is 25% wider by diameter is actually 56% larger by area.
When feeding a group, the price per square inch comparison almost always favours the larger size — split one large pizza rather than buying two mediums.
Personal pizzas (9–10 inches) typically have the worst price per square inch but are useful for individual dietary preferences or allergies.
Crust preference matters: a larger pizza has proportionally less crust per slice if slice count is similar — the centre-to-edge ratio improves with size.
For baking at home, pan diameter directly sets the pizza area — use this calculator to check whether your home pan size matches the recipe's intended yield.

A 16-inch pizza has 78% more area than a 12-inch, despite a diameter that is only 33% larger — the square relationship makes large sizes dramatically better value.
Two 12-inch pizzas have a combined area of 226 sq in; one 16-inch has 201 sq in — two mediums beat one large by area, but one large almost always wins on price per square inch.
Increasing pizza diameter by 2 inches (e.g. 12" to 14") adds approximately 36% more area — a meaningful jump for a small price difference at most restaurants.
A standard 8-slice cut of a 12-inch pizza gives approximately 14.1 sq in per slice; the same 8-slice cut of a 16-inch gives 25.1 sq in — 78% more per slice.

Common mistakes to avoid

Comparing pizza sizes by diameter rather than area — a 16-inch pizza is not 33% larger than a 12-inch; it is 78% larger by area because area scales with the square of the radius.
Assuming two small pizzas equal one large — two 12-inch pizzas (226 sq in) exceed one 16-inch (201 sq in) by area, but the pricing per square inch usually favours the large.
Ignoring crust thickness — this calculator computes surface area, not volume; a thick-crust pizza has more dough per square inch than a thin-crust and will be more filling.
Not adjusting slice count — a pizza split into 6 slices gives noticeably larger slices than one split into 10; the area per slice changes significantly with cut count.

Pizza sizes stated by restaurants are nominal diameters. Actual baked pizzas may be slightly smaller due to crust shrinkage — a 16-inch nominal pizza may bake to 15–15.5 inches. Prices, portion sizes, and serving recommendations vary by restaurant, region, and crust style. This calculator is for comparison and planning purposes only.