Hamburgers are a staple at many fast-food restaurants, but the calorie count can be difficult to discern. The number of calories in a fast-food hamburger will vary with its size, condiments and type of preparation.
According to the United States Department of Agriculture a typical plain single-patty fast-food hamburger has 254 calories. The same hamburger with condiments added has 294 calories, while the large version of the plain hamburger has 426 calories.
Calories from Fat
Medline Plus reports that each gram of fat provides 9 calories. For the regular plain hamburger, its nearly 10 g of fat account for more than 87 calories from fat. The regular hamburger with condiments has more than 11 g of fat for more than 103 calories of the total. The large hamburger also has a large fat count, with its nearly 23 g of fat adding more than 206 calories from fat.
Calories from Carbohydrates
Every gram of carbohydrates has 4 calories. The plain hamburger has nearly 29 g of carbohydrates for almost 116 calories from carbs; its condiment-bearing counterpart has nearly 33 g of carbohydrates for more than 131 calories. The large plain hamburger needs a larger bun and has almost 32 g of carbohydrates for the trouble, counting for almost 127 of its total calories.