HELP Trying to calculate calories in a taco meal

pb6012002

I have 2.53 pounds of ground beef that I am going to make tonight and add two packages of Old El Paso taco seasoning. I am trying to figure out how many calories are in it. Obviously I am not going to eat all of it LOL But normally with tacos I eat until I am busting. HELP. I have Low fat Sargento mexican mix cheese and tomatoes I can add to it. And I even have a low calorie tortilla I can use just need to know how to measure out the meat. Thanks in advance.