The calories of a cheese sandwich vary based on the types of bread and cheese used, ranging from under 250 to over 400 calories. One slice of American cheese on white bread with margarine is about 200 calories, while 3 ounces of cheddar on buttered, gluten-free bread exceeds 400 calories.
Using one pat of butter to butter the bread adds 36 calories, while margarine adds 34. One 19-gram slice of American cheese has 45 calories, while a slice of cheddar cheese has about 90 calories. One slice of bread ranges from 65 calories for white to 78 calories for whole wheat or 90 calories for gluten free.