How to Calculate Portion Size
Calculate portion size by dividing the recipe's total cooked yield by its number of servings, then multiply one serving by the number of people eating.
This method works for home meals, meal prep, parties, and catering, whether you measure by weight, volume, pieces, or package count.
Kids are counted as about 60% of an adult portion. Appetite and leftover adjustments are shown in the result.
Shopping list
- Dry pasta2.76 lb
- Pasta sauce5.5 cups
- Parmesan cheese5.3 oz
Info: 75–100g dry pasta per adult for a main dish. Cooked weight ~2.25× dry.
The portion-size calculation
First find the finished yield, not just the raw ingredient weight. Weigh the cooked recipe or measure its total volume, subtracting the empty container if necessary. Divide that yield by the intended number of servings. A casserole weighing 80 ounces and labeled for 10 servings provides an 8-ounce portion. For 25 people, 25 portions require 200 ounces, or 12.5 pounds.
For individual foods, begin with a standard per-person amount: roughly 4 to 6 ounces cooked protein, 1 cup cooked starch, or 1 to 2 cups vegetables for an adult meal. Multiply by the adult guest count, count younger children at about 60 percent, and add a chosen buffer. Convert the result into packages only after calculating the total amount.
Raw weight, cooked yield, and waste
Many foods change weight during preparation. Dry rice and pasta gain water, while meat loses moisture and fat. Bone, peel, shells, and trimming also reduce edible yield. If meat has a 75 percent cooked yield, divide the cooked amount needed by 0.75 to find the raw purchase weight. Ten pounds cooked therefore needs about 13.3 pounds raw.
Write down assumptions so the plan can be adjusted. Note whether a figure is raw or cooked, whether the dish is a main or side, and whether seconds are included. Round up to whole packages, but avoid adding the same safety margin at every step. One clear 10 to 15 percent event buffer is usually more accurate than repeated rounding that creates excess food.