Pizza Size Calculator
Compare up to three pizzas by area instead of diameter. A 16-inch is not twice a 12-inch — it is 1.78 times — and price per square inch shows which deal really wins.
Pizza Size Calculator: with the default inputs, best value is Pizza 2 — 16″ at $18.99.
The advertised size — pizzas are sold by diameter, which is exactly why the deals are confusing.
What you pay in total for that many. A 'two for $22' deal is 22 with a count of 2.
Set this to 2 to price a 'two for' deal — the price above is then the total for both.
- Best price per square inch
- $0.094
- Pizza 2 ÷ pizza 1 area
- 1.7778Area scales with the square of the diameter, so this is (d₂ ÷ d₁)².
- What that means
- One 16-inch pizza has 1.78× the area of a 12-inch — the diameter is only 1.33× bigger, but area goes as the square.
- Pizza 1 — per square inch
- $0.133
- Pizza 2 — per square inch
- $0.094
- Pizza 3 — per square inch
- $0.127
- Pizza 1 area (each)
- 113.1 in²
- Pizza 2 area (each)
- 201.1 in²
- Overpaying by choosing the worst option
- $7.66 extra for the same 201 in² of pizza ($0.038 per square inch).Extra cost to buy the same amount of pizza from the worst-value option instead of the best.
Assumptions
- Pizzas are treated as perfect circles at their advertised diameter.
- Area includes the crust; topped area is not deducted.
- The price field is the total for the quantity entered, not the price of one pizza.
- Price per square inch is always reported in square inches even when diameters are entered in centimetres.
| Size | Total area (in²) | Price | Per in² | = how many pizza 1s | ||
|---|---|---|---|---|---|---|
| Pizza 1 | 12″ | 113.1 | $14.99 | $0.133 | 1 | 40% dearer per in² |
| Pizza 2 | 16″ | 201.1 | $18.99 | $0.094 | 1.78 | ◀ best value |
| Pizza 3 | 10″ × 2 | 157.1 | $19.98 | $0.127 | 1.39 | 35% dearer per in² |
Area is the whole circle, crust included. If you leave the crusts, the topped area falls faster than the total for small pizzas.
How this is worked out
The formula
area = π × (diameter ÷ 2)² total area = area × quantity price per square inch = price ÷ total area area ratio between two pizzas = (d₂ ÷ d₁)²
Open How it’s calculated above to see this worked through with your own numbers.
What you enter
- Pizza 1 diameter
- The advertised size — pizzas are sold by diameter, which is exactly why the deals are confusing.in in, cm · from 1 to 40 · defaults to 12
- Pizza 1 — total price
- What you pay in total for that many. A 'two for $22' deal is 22 with a count of 2.in dollars · 0 or more · defaults to 14.99
- Pizza 1 — how many
- Set this to 2 to price a 'two for' deal — the price above is then the total for both.from 1 to 20 · whole numbers only · defaults to 1
- Pizza 2 diameter
- A number.in in, cm · from 1 to 40 · defaults to 16
- Pizza 2 — total price
- A number.in dollars · 0 or more · defaults to 18.99
- Pizza 2 — how many
- A number.from 1 to 20 · whole numbers only · defaults to 1
- Pizza 3 diameter(under More options)
- Set to 0 to leave the third option out.in in, cm · from 0 to 40 · defaults to 10
- Pizza 3 — total price(under More options)
- A number.in dollars · 0 or more · defaults to 19.98
- Pizza 3 — how many(under More options)
- A number.from 1 to 20 · whole numbers only · defaults to 2
What you get back
- Best valuemain answer
- Best price per square inch
- Pizza 2 ÷ pizza 1 area
- Area scales with the square of the diameter, so this is (d₂ ÷ d₁)².
- What that means
- Pizza 1 — per square inch
- Pizza 2 — per square inch
- Pizza 3 — per square inch
- Pizza 1 area (each)
- Pizza 2 area (each)
- Overpaying by choosing the worst option
- Extra cost to buy the same amount of pizza from the worst-value option instead of the best.
What this assumes
- Pizzas are treated as perfect circles at their advertised diameter.
- Area includes the crust; topped area is not deducted.
- The price field is the total for the quantity entered, not the price of one pizza.
- Price per square inch is always reported in square inches even when diameters are entered in centimetres.
About this calculator
Pizzas are sold by diameter and eaten by area, and those two numbers do not scale together. Double the diameter and you quadruple the pizza. That single fact settles most of the arguments people have at the counter.
The number that surprises everyone
A 16-inch pizza is not a third bigger than a 12-inch. Its area is 16² ÷ 12² = 256 ÷ 144 = 1.78 times larger — nearly two 12-inch pizzas in one box. An 18-inch has 2.25 times the area of a 12-inch. Two 10-inch pizzas come to 157 in², which just edges out a single 14-inch at 154 in² — and both are beaten outright by one 16-inch at 201 in². Because area grows with the square of diameter, the larger pizza wins on price per square inch far more often than the menu makes it look.
How to use it
Enter the diameter and price for two pizzas. The price is the total you hand over for that many, so the quantity field prices "two for" deals directly: set it to 2, put the deal price in, and the calculator compares total area against total price, which is the only fair comparison. Open More options for a third option, or set its diameter to 0 to leave it out. Diameters can be entered in centimetres if that is how your local menu works; the ratio is unit-free either way.
Reading the results
Price per square inch is the honest unit price. Chains commonly run 8–12 cents per square inch for a plain large and 14–18 for a small, which is why the small is almost never the deal. The area ratio shows how the two sizes really compare. Overpaying puts a dollar figure on picking the worse option for the same amount of food.
The caveats worth knowing
- The maths assumes a circle. Real pizzas run under their advertised diameter, and a "16-inch" from two shops may differ by half an inch.
- Crust is counted in the area. If you leave crusts, the edible fraction is π(r − c)² ÷ πr², which punishes small pizzas: a one-inch crust costs a 10-inch pizza 36% of its area but a 16-inch only 23%.
- Toppings do not scale with area on every menu — some chains use the same topping weight across two sizes, so the bigger pizza can be thinner on top.
- Deep dish, pan and stuffed crusts carry more dough per square inch, so area is not the whole story on how filling a pizza is.
Pizza per person runs about 60–80 square inches for an adult with a side, more for teenagers, less if there are wings. Total the area you need first, then find the cheapest way to buy it.
Frequently asked questions
▸Is a 16-inch pizza twice as big as a 12-inch?
No — it is 1.78 times as big. Area is π(d÷2)², so the ratio is 16² ÷ 12² = 256 ÷ 144 = 1.7778. You would need a 17-inch pizza to double a 12-inch.
▸Is one large pizza better than two mediums?
Usually, but check the areas. Two 12-inch pizzas give 226 in² against one 18-inch at 254 in², so the single large wins on food — and normally on price per square inch too.
▸How much pizza does one person eat?
Roughly 60–80 square inches, which is about two slices of a 16-inch (eight slices, 25 in² each) or three slices of a 12-inch. Order by total area rather than by pizza count.
▸How do I compare pizzas of different prices and sizes?
Divide the price by the area in square inches, not by the diameter. Price per square inch is the only comparison that survives different sizes and multi-buy deals.
▸Does the crust count?
This calculator counts the whole circle. If you never eat the crust, subtract it: edible area is π(r − crust width)², which hits small pizzas much harder than large ones.
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