Pizza Size Calculator
Compare two pizza sizes and see which one actually gives you more pizza for your money — area grows much faster than diameter alone suggests.
How to use the calculator
- Enter the diameter and price for the first pizza.
- Enter the diameter and price for the second pizza.
- See which one has the lowest price per square centimeter — the better deal per bite.
How it's calculated
Many people mistakenly assume a pizza with double the diameter has double the food — but area grows with the square of the diameter. A 40 cm pizza has nearly double the area of a 30 cm pizza (1.78×), not just 33% more, even though the diameter is only 33% larger.
Diameter lies — area is what counts
A 40 centimetre pizza is not a third bigger than a 30 centimetre one — it is almost twice the size. Area grows with the square of the diameter, so a one-third increase in diameter produces an increase of nearly eighty percent in the amount of pizza. That is why two small pizzas almost never equal one large, even when the diameters look as though they should add up.
Work out the price per square centimetre rather than per pizza and the comparison is usually decisive in favour of the largest size. The exception is the crust: a larger pizza has proportionally less edge per unit of area, which is an advantage if you are after topping and a drawback if the crust is the part you like best.
Frequently asked questions
Is a large pizza almost always cheaper per cm²?
Often, yes — many pizzerias don't price proportionally to area, so larger sizes tend to offer better value. But it varies, and this calculator lets you check your specific offer instead of assuming.
Why does a 40 cm pizza feel so much bigger than a 30 cm one?
Because our brains tend to think linearly (diameter), while the actual amount of food follows area — a squared relationship that produces a surprisingly large difference.
Can I use this to compare more than two pizzas?
The calculator shows two at a time, but you can easily run it multiple times and note the price per cm² for each, then compare the numbers yourself.