The Twitter Pizza Equation Explained

A math equation of how to ensure more pizza per order sparks a debate on Twitter. Quite a revelation, right? Well, and it left many pizza lovers around the world ‘cheated’ and perplexed. While others argued that this is a perfect example to show why maths is important.


Hungry for some pizza? We all like a good pizza pie to chow down on, but it turns out there’s a simple scientific solution to maximize your pizza experience.

It all comes down to the area of a circle – that equation you may have heard of when you were young, where the area is equal to pi*r². “r” being the radius. If we plug in some numbers, you may notice something interesting.

For example, since we measure pizza in inches in North America, the area of an 8-inch pizza is roughly 50 square inches. We take the radius of the pizza, which is half of the diameter, so 4 inches, in this case, put it in the equation, and voila.

But if we do the same thing for a 16-inch pizza, which has a diameter that is two times bigger, we find that, even though your intuition may say it’s twice as big, it has an area of over 200 square inches, which is four times more pizza. This is because the area of a circle increases with the square of the radius.

And yet, most of the time, the difference in price between an 8-inch pizza and a 16-inch pizza is not even two times more expensive – let alone four times more expensive. In fact, NPR did a study of over 74,000 pizza prices in America and created an interactive graph to show exactly how the price of pizza changes with size and how much more pizza you get when you order a large.

For example, a 20-inch pizza has more area than two 14 inch pizzas or six 8 inch pizzas. Yet it’s almost nine dollars cheaper on average than getting to 14-inch pizzas and over thirty dollars cheaper on average than getting six 8 inch pizzas. And this is the pizza equation: The bigger the diameter of the pizza, the more bang for your buck.

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