Pizza Size Calculator
Which pizza is the better deal? Compare round and rectangular sizes by area and price per square inch or centimetre, or work out how many pizzas a group needs.
Result…
How it's calculated
Round: area = π × d² ÷ 4 · Rectangular: area = width × length Price per unit area = price ÷ area · 1 in² = 6.4516 cm² Pizzas to order = ⌈people × slices per person ÷ slices per pizza⌉
Pizza is sold by diameter but eaten by area, and area grows with the square of the diameter: a 40 cm pizza has 1.78 times the area of a 30 cm one, not 1.33 times. So the bigger pizza is often the better deal even at a higher price. Enter each pizza's size and price, round or rectangular, in centimetres or inches, and the calculator gives the area, the price per square centimetre and per square inch, and which one costs least for the amount of pizza. Inches convert at exactly 2.54 cm. The second mode counts pizzas for a group from the slices each person eats and the slices in a pizza.
Your numbers, step by step
About the Pizza Size calculator
This pizza size calculator answers the question every menu raises: is the large really better value than two mediums? Pizzas are sold by diameter but eaten by area, and area grows with the square of the width, so a pizza a third wider has almost twice as much to eat. Enter each pizza on its own line with a name, a size and a price: a single number for a round pizza's diameter, or width x length for a rectangular tray. Sizes work in centimetres or inches, and every result is shown in both, converted at exactly 2.54 cm to the inch. You get each pizza's area, its price per square centimetre and per square inch, and which one costs least for the amount of pizza. A second mode counts how many pizzas to order for a group, from slices per person and slices per pizza.
How to use it
- Leave “Work out” on “Best value” and pick “Centimetres” or “Inches” under “Sizes in”.
- List the pizzas in “Pizzas, one per line: name, size, price”, like “Large 40 15.00” or “Tray 30x45 18.00”.
- Read the best value, then each pizza's area and price per square unit, and how much more pizza the winner gives for the money.
- To plan a party, choose “Pizzas for a group” and enter “People”, “Slices per person”, “Slices per pizza” and, if you like, “Price per pizza”.
Worked example
A 30 cm medium costs 9.50, a 40 cm large costs 15.00 and a 30 × 45 cm tray costs 18.00. The medium's area is π × 30² ÷ 4 = 706.9 cm² (109.6 in²), so it costs 0.01344 per cm². The large has 1,256.6 cm² (194.8 in²) at 0.01194 per cm², and the tray 1,350 cm² at 0.01333 per cm². The large is the best value: it gives 11.7% more pizza for the money than the tray, the next best. For a party of 10 eating 3 slices each from 8-slice pizzas, order 4 pizzas: 32 slices, with 2 left over.
Updated
Questions people ask
How do I work out the area of a pizza?
For a round pizza, area = π × diameter² ÷ 4, so a 30 cm pizza has about 706.9 cm². For a rectangular one, multiply width by length. The circle area calculator does the round case on its own.
Is one large pizza better value than two mediums?
Often, because doubling the diameter quadruples the area. A 40 cm pizza has 1.78 times the area of a 30 cm one, so it is better value whenever it costs less than 1.78 times as much. Enter both with their prices to check.
What does price per square inch mean for pizza?
It is the price divided by the area, the cost of each square inch you eat. The lower it is, the more pizza you get for your money; the calculator gives it per square centimetre too.
How many pizzas do I need for a party?
Multiply the number of people by the slices each will eat, divide by the slices in one pizza and round up. Ten people at 3 slices each need 30 slices, which is 4 pizzas of 8 slices.
Is comparing by area always fair?
Area tells you how much surface you get, but crust width, thickness and toppings vary, and shops measure stated sizes differently. For other price-per-unit comparisons, such as pack sizes in a shop, try the unit rate calculator.