What this calculator does
Find out which pizza gives you the most food for your money. Pizza is sold by diameter, the distance straight across, but you eat its area. And area grows with the square of the diameter. A 16 inch pizza is only a third wider than a 12 inch one, yet it has almost 78% more pizza. That is why the price of a size, on its own, says little about value. This calculator works out the area of each pizza and the price you pay per 100 square inches, then names the best deal.
Compare two pizzas, or add a third. Each one can be a multi-pizza deal, so the classic question of two medium pizzas against one large is a single calculation. Diameters can be in inches or centimeters.
Where it's used
Why this math matters outside the classroom:
- Ordering for a group. A family compares a $20 large of 18 in (254 in²) with two $10 mediums of 12 in (226 in² in total).
- Circle area lesson. Students find that doubling a pizza from 7 in to 14 in multiplies its area by 4, from 38.5 in² to 153.9 in².
- Unit pricing. Shoppers turn $18 for 201 in² into $8.95 per 100 in², the same idea as price per ounce.
- Menu pricing. A pizzeria owner checks that each larger size costs less per square inch so customers are rewarded for upsizing.
- Club budgets. A student club with $60 for snacks buys the size with the lowest price per area to feed the most members.
Grade level and standards: Grades 6–7; Common Core State Standards for Mathematics 7.G.B.4, 6.RP.A.3.b. © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved.
How to use it
- Choose inches or centimeters.
- Enter each pizza's diameter and price. If a deal includes several of the same pizza, enter the price of each and the number of pizzas.
- Optionally enter a third pizza to compare.
- Read the best value and the price per 100 square inches (or square centimeters) for every option.
What the inputs mean
- Pizza A diameter
- Menus quote the listed diameter. Measure across the middle if you can. A pizza listed as 12 in is sometimes a little smaller, and that changes the area noticeably.
- Number of pizza A
- Two 12 in pizzas at $10 each: enter 12, 10 and 2. The price is per pizza, and the total is price × number.
- Number of pizza B
- For deals like two medium pizzas.
- Pizza C diameter
- Optional third pizza to compare.
Formula and method
area of one pizza = π × (diameter ÷ 2)² total area = area × number of pizzas price per 100 square units = total price ÷ total area × 100 best value = the lowest price per 100 square units
A round pizza's area is π times the radius squared. π (pi) is about 3.14, and the radius is half the diameter. Squaring makes size matter more than intuition suggests: doubling the diameter quadruples the area.
Dividing the total price by the total area gives a unit price, like the shelf labels in a supermarket. It is quoted per 100 square inches (or 100 cm²) so the numbers are easy to read. The pizza with the lowest unit price gives the most pizza per dollar.
Worked example
A 12 inch pizza costs $12 and a 16 inch pizza costs $18. Which is the better deal?
- 12 in pizza: π × 6² = 113.1 in²; $12 ÷ 113.1 × 100 = $10.61 per 100 in².
- 16 in pizza: π × 8² = 201.1 in²; $18 ÷ 201.1 × 100 = $8.95 per 100 in².
- The 16 in pizza has 1.78 times the area for 1.5 times the price, and costs 15.6% less per square inch.
Result: The 16 inch pizza is the better value at $8.95 per 100 square inches.
Understanding the result
A lower price per area means more pizza for each dollar. Bigger pizzas usually win, because the cost of the dough, oven time and box doesn't grow as fast as the area.
Value isn't everything: if the extra pizza goes to waste, the smaller one may be the cheaper meal. Use the area figures to judge how much food each option gives.
Assumptions and limitations
- Pizzas are round and the diameter is measured edge to edge, crust included.
- Crust thickness and toppings are the same across the options being compared.
- Prices are per pizza before tax, delivery and tip.
- The outer crust counts as area here. If you don't eat it, a larger pizza is even better value, because the crust ring is a smaller share of its area.
- Square or rectangular pizzas aren't covered. For those, use length × width for the area, along with the unit price calculator.
- Coupons, delivery fees and tips change the real cost. Include them in the price if you want to compare them.
Frequently asked questions
Are two medium pizzas more than one large?
Often not. Two 12 inch pizzas have about 226 in² in total, while a single 18 inch pizza has about 254 in². Enter both deals to compare their price per area.
How much bigger is a 16 inch pizza than a 12 inch?
About 78% bigger by area: 201 in² against 113 in². The ratio of the areas is (16 ÷ 12)², or 1.78.
Why is the price per area shown per 100 square inches?
The price per single square inch is a few cents and hard to compare at a glance. Multiplying by 100 gives numbers like $8.95, which are easier to read. The ranking stays the same.
What if two pizzas have the same price per area?
Then they are equally good value per bite, and the calculator says so. Choose by how much food you need.
How this calculator is checked
Method: Area of a circle (π r²) and unit price (total price ÷ total area), scaled to 100 square units. The calculation is covered by automated tests with known reference values and edge cases. Last updated 2026-10-18. Found a problem? Tell us.
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