How Many Calories Are in a Tuna Sandwich?

If your pantry includes tuna, you're hardly alone. According to the National Fisheries Institute, consumers in the United States enjoy more than a million pounds of tuna annually. Although eating the canned fish on its own might not thrill you, mixing it with mayonnaise and spreading it between two slices of fresh bread can be a hearty snack -- albeit one that's fairly high in calories.

Although you can prepare your tuna sandwich with a variety of twists, the standard approach to the snack is mixing the fish with mayo. According to the U.S. Department of Agriculture, a 172-gram can of tuna has 220 calories. If you mix the contents of the can with two tablespoons of reduced-fat, olive oil mayonnaise, you add about 108 calories to the mix. Two slices of white bread increases the meal's caloric count by 148 calories; if you'd rather use whole-wheat bread, two slices equal 162 calories. Thus, a standard tuna sandwich on white contains 476 calories, while a whole-wheat tuna sandwich has 490 calories. To lower the calories, you could mix the tuna with low-fat, plain Greek yogurt.