Calculate a round pizza’s area, optional slice and crust split, price per square inch, or an equivalent diameter. Compare quantities of two pizza sizes using full or topping-only area.
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Pizza Area Formula
The calculator uses the area of a circle, with the pizza diameter as the input.
- A = pizza area (square inches)
- D = pizza diameter (inches)
- pi ≈ 3.14159
If you enter a crust width c, the topping area uses the inner diameter:
Per-slice area divides total area by the number of slices:
In Compare mode, the calculator computes total counted area for each option and, if you enter prices, the cost per square inch:
Assumptions: pizzas are round, the crust ring has a uniform width, and all length inputs are converted to inches before computing area. Square centimeters use 1 in² = 6.4516 cm².
Calculator modes:
- Area and value: returns total area and circumference, with per-slice area, price per area and topping/crust split when you supply those optional inputs. Equivalent diameter mode solves from a known area.
- Compare two options: compares total full or topping-only area for each size and quantity, plus price per area when prices are entered. Blank prices omit value comparisons; zero means free.
Common Pizza Sizes and Areas
Use this as a quick reference for menu sizes. Areas are based on the full pizza, no crust exclusion.
| Diameter | Area (sq in) | Area (sq cm) | Slice (8 cut) |
|---|---|---|---|
| 8 in (small) | 50.3 | 324 | 6.3 |
| 10 in | 78.5 | 507 | 9.8 |
| 12 in (medium) | 113.1 | 730 | 14.1 |
| 14 in (large) | 153.9 | 993 | 19.2 |
| 16 in (XL) | 201.1 | 1,297 | 25.1 |
| 18 in | 254.5 | 1,642 | 31.8 |
| 20 in | 314.2 | 2,027 | 39.3 |
Two Smalls vs One Large
Compare total area and total price. A larger diameter alone does not establish better value; quantity, crust exclusion and price can change the comparison.
| Option | Total Area | Vs alternative |
|---|---|---|
| Two 12 in | 226.2 sq in | +12% over one 16 in |
| One 16 in | 201.1 sq in | baseline |
| Two 10 in | 157.1 sq in | −22% vs one 16 in |
| One 18 in | 254.5 sq in | +65.3% vs one 14 in |
Worked Example and FAQ
Example: 16 in pizza, 8 slices, 1 in crust
Total area: pi * 8^2 = 201.06 sq in.
Per slice: 201.06 / 8 = 25.13 sq in.
Topping area with a 1 in crust: pi * (8 - 1)^2 = pi * 49 = 153.94 sq in. That means the crust ring takes about 24% of the pizza.
Why does diameter matter so much?
Area scales with the square of the diameter. A 16 in pizza is not 33% bigger than a 12 in pizza, it is 78% bigger. Bumping up two inches usually adds more food than people expect.
How do I compare price fairly?
Choose Compare two options and enter each price and quantity. The calculator divides total price by total counted area to give cost per square inch. Lower cost per area is better value on this area-only basis; thickness, toppings and quality are not measured.
Should I exclude the crust?
Exclude the crust only for a topping-only comparison, such as when you do not eat the rim. Measure the actual uniform rim width for each pizza; style names do not establish that measurement.
How many people does a pizza feed?
Portions depend on appetite, pizza thickness, other food and slice size. Area alone does not determine how many people a pizza feeds; use your intended portions for order planning.
What if my pizza is square or rectangular?
This calculator handles round pizzas. For a square or Detroit style pizza, multiply length by width directly instead of using the circle formula.
