The term "jumbo shrimp" isn't regulated and can mean different things in different stores. It's better to buy based on the count listed on the bag, which tells you how many shrimp are in each pound. The fewer shrimp in a pound, the larger the size of each shrimp. There may be as few as seven or eight shrimp per pound of shrimp labeled "jumbo."
The cooking method you use will affect the number of calories per serving of shrimp. A 3-ounce serving of shrimp cooked with moist heat contains about 101 calories. If there are eight jumbo shrimp in a pound, that means each shrimp weighs about 2 ounces and has approximately 67 calories. If you bread and fry your shrimp, the calorie content increases to 206 in a 3-ounce serving and 137 per jumbo shrimp.