Figuring out calories and such for a meal is actually pretty simple. It's not exact, but it is close. What you do is to check each ingredients nutritional information per serving. Add all the information together and you have your number.
My wife and I are staying at about 1500 cal/day, and our meals are family meals. We have two boys. Our dinner is usually under 500 calories. We also create a menu for the week, and post it on the fridge. Not only do I now have a shopping list, but I can figure out my calories per meal that way. It also helps curb the spontaneous dinners. We were notorious for saying "what do you want for dinner"? 50% of the time it was fast food. Since we started this menu, we have only eaten fast food (pizza) once since the end of December. The added bonus is we spend less on food by not eating out!