How do you fit a 19-inch pizza into an 18-inch box?

That’s a question the Concord Monitor decided was worth exploring.

Concord is fortunate enough to have not one but three Market Basket supermarkets. Unlike the other two, the newest one at the Merchants Way shopping plaza in Penacook sells 19-inch pizzas from its kitchen for the affordable price of $8.99 – plus $2 per topping. But anyone who has ordered one may have noticed something on the bottom of the box – a large 18” printed in big red type.

We wondered if putting 19-inch pizzas in 18-inch boxes was a situation similar to “footlong” subs coming up a little short. We bought three pizzas (with different toppings, for a more varied sample) and brought out the big guns: a yardstick.

Before we measure, though, let’s back up. Pizzas usually come in even sizes, like 12, 16 and 18 inches. The number 19 is an anomaly in the pizza world, which is why large pizza boxes typically are either 18-by-18 or 20-by-20.

Accurately measuring a pizza is more difficult than you might anticipate. A ruler from crust to crust offered a diameter, but our results differed slightly depending on the exact points we measured. Any given throughline came out to be as short as 17.5 inches or as long as 19.5.

We thought we had a breakthrough when someone had the idea to measure the circumference of the pizza using a piece of string, and then divide it by pi to find the average diameter. With five reporters and a handy pack of dental floss, we found the pizza to be 60 inches around the crust – which, when divided by pi, comes out to 19.09.

The newsroom erupted with excitement. But it was cut short by an unwelcome epiphany hailing from deep within middle-school memory: the equation only works if the pizza is a perfect circle. It was not.

In fact, since pizza is almost never perfectly circular, its true diameter is just about impossible to calculate.

This was a disappointing revelation, but we didn’t stop there.

It occurred to us that the answer to the exact size of the pizzas, which are made by human hands after all, could have more to do with how it’s put into the box.

A new theory emerged: If the pizza was squished down to 18 inches across in certain places so it could fit in the box, it could bulge out in the corners a bit, which is where the 19-inch measurements came from. Or, the dough might get a bit thicker in those parts – but it’s still the same amount of food.

Ultimately, it came down to math. If the pizza were a perfect circle and fit inside the 18-inch square box, it would be about 254.5 square inches. The total area that the box can accommodate (if the pizza were a square) is 324 square inches. The true area of the pizza falls somewhere in between.

A circular 19-inch pizza would yield an area of 283.5 square inches. It’s entirely possible Market Basket could be serving up the promised amount of oblong pizza within the box.

The explanation could be simple: Think about all that wasted space and cardboard if Market Basket used 20-inch boxes to hold its 19-inch pizzas. Plus, maybe you’ll be lucky and get undercharged for the pizzas, like me. Whether the pizzas are squished, irregular, or just a bit smaller than they’re supposed to be, Market Basket isn’t ripping you off. And for that, they remain a regional favorite.