A viral Reddit post showing the varied prices of Big Macs across the country has prompted discussion and questions about franchise pricing.

The McDonald's signature burger with special sauce sets a diner back $7.59 at a Massachusetts Turnpike service plaza in Lee, Mass., which is reportedly the most expensive in the nation.  

"Pricing is determined at the restaurant-level by franchisees and may vary based on location," according to McDonald's USA.

That also goes for other franchises like Burger King and Dunkin'.

According to the Division of Consumer Protection, businesses may charge any price they deem necessary as long as the correct price is being advertised. It notes there's a variety of factors franchisees consider when coming up with costs.

So, what exactly are those factors? Franchisee consultant John Adams explained.

"For pricing structure in a restaurant, you have basic food cost, cost of goods sold, which includes labor," said Adams. "These are used to determine the price of a product that's being sold."

Adams has held a variety of positions with Domino's, assisting the largest franchisee in the state of New York.

"When you're talking about using a food cost to determine the price of a product being sold is between 2.5 and maybe five times the actual cost of the food that it's being sold at," Adams said.

From how to stretch a pizza to what box it goes in, there are standards each franchise has to follow. But price typically isn't one of them.

"Typically, there's a range because different regions have different costs," said Adams. "And the pricing is directly related to the cost of the product that they're selling."

So whether it’s roadside dining or in the city that never sleeps, Adams said it’s leasing costs that play the largest role in pricing.

"From top to bottom, there is playbook," said Adams. "It tells you how to do your business. And that's why franchising has worked so well over the years, because there's successful practices that are put into that guidebook."

While you may find variations in how much something costs, Adams said you shouldn’t find much difference in ingredients and taste.