The recipe nutrition calculator I use lets you put in how many servings it makes. That is completely up to you. You can measure it out if you like or just divide it by eyeballing. For example, I make a (lowfat, folks!) chicken pot pie in a 9 X 13 pan and consider it 8 servings. I put the ingredients and the number of servings in and then I know that each time I eat an eighth of it, it's one serving that goes into my food journal. If I eat twice that much, it's 2 servings. If I eat one eighth and then half of another eighth, it's 1.5 servings I enter into FitDay.
If I'm making something like marinara sauce, I measure out how many cups there are (that gives me my number of servings) and then can make a cup or a half cup a serving.
When I create the custom food in FitDay, I usually put the serving size from the recipe in parentheses after the name I give the food, and adjust the number of servings as above when I enter what I actually ate.
It's kind of time consuming and confusing but it's worth it to me to know what I'm eating, especially on the homemade stuff.
Different foods have different typical serving sizes, so it's hard to answer that part of your question. I would imagine that a serving needs to consistently work within your calorie/macronutrient plan to be a good serving size.
And now that you don't have to be perfect, you can be good.
Last edited by cjohnson728; 02-17-2010 at 04:55 AM.