The average size of a filet mignon is 6 ounces, and it contains about 242 calories uncooked. The calorie count is changed considerably by cooking methods, as well as any sauces used on the meat.
When grilled or baked with only light seasonings and no oil, a filet mignon retains its uncooked calorie count. Salt, pepper, garlic and onion powder impact the calorie count only marginally. Savory herbs can be used without a large increase in calories. However, using oil or butter adds calories. Creating a reduction or other sauce also increases the number of calories in the finished steak.