Your from-scratch recipe might looks scrumptious, but there's no label to tell you how big a serving should be. To figure that out, you'll need to weigh the dish and calculate how much each serving will weigh from there.
Weigh the Dish
Before you can accurately divide your recipe into servings, you need to know how much the entire dish weighs. Weigh the food not counting the weight of the dish it is contained in. For most recipes, you'll either need to weigh the pot or pan before you begin cooking and subtract it from the final weight, or you'll need to transfer the food to a new dish after cooking. If you're transferring the food to a new dish, weigh the empty dish first and either record its weight to subtract from the total or zero in your scale to account for it. Weigh the finished recipe in the new dish to find its total weight.
Divide the Recipe Into Servings
Once you know how much the entire finished dish weighs, divide the weight by the number of servings in the recipe, which is usually listed in the recipe. Round the result to a memorable number to find the average serving size. For example, if your casserole weighs 92.86 ounces and yields 8 servings, the result would be 11.607, which you would then round to a memorable 11.5 ounces per serving. Divide the recipe into weighed individual servings after calculating their size if you don't want to use the scale every time you'd like a helping.
For Recipes Without Serving or Calorie Information
If your recipe does not tell you how many servings it yields, you will need to determine this yourself. One way to do this is by using a calorie counter. Use an online food catalog like the USDA National Nutrient Database to find information for each ingredient. Add the calories from each ingredient to find the dish's total calorie count. Next, you can decide how many calories you want in each serving. For example, if you keep each meal to 250 calories, divide the calories in the recipe by 250. Round the resulting number to make a whole number -- this is how many servings the recipe yields. If the recipe has 1,289 calories, divide it by 250 to equal 5.15, round that down to five and you have the number of servings in the recipe.
Save the Information
Calculating serving size information for a recipe is time consuming and can dirty extra dishes. Save the information for every recipe that you calculate so you will have it on hand if you make it again. All you have to do the next time around is weigh individual servings according to the predetermined weight.