I use two calculators, spark for solid dishes that can easily be divided, and nutritiondata for things like soups where you would like a weight per serving. If you don't weigh your foods then sparkrecipes calculator would be fine to "ballpark" a serving. You can estimate how many servings per pot then input the ingredients.
Here is the spark calculator. Its awesome, but doesn't give you the weight per serving:
http://recipes.sparkpeople.com/recipe-calculator.asp
Here is the link for nutrition data. It is more time consuming because you need to weigh every ingredient in the soup including water. I find it great though because the end result will tell you exactly what a serving weighs so you will know how much to eat. You can save the recipe and just adjust it when you add a new ingredient to your soup recipe.
http://nutritiondata.self.com/mynd/m...mynd/myrecipes