Markup on food is necessary. Restaurant owners may not pay much for individual ingredients, but they still have bills and wages to pay. Ever wonder how much that extra slice of cheese really is?

For most restaurants to break even on their costs, they have to charge about 300% more than they paid for their ingredients.

On average, for an extra piece of cheese on your burger you'll be spending 417% of the cost. The $1.50 you pay is up from the 29 cents the restaurant bought the cheese for. Burgers aren't the only targets of crazy markup, take a look at these popular add-ons:

Plate IQ

MarketWatch has a closer look at the markup of other food items.