Dry spaghetti doesn't easily fit into a measuring cup, which can make it difficult to measure out enough for the meal. Portion sizes depend on your diner's appetites, but learning how to gauge the standard serving size will allow you to adjust the portions upward or downward as needed.
A standard serving size of dried spaghetti is 1 ounce, which yields about ½ cup of cooked pasta, but those with big appetites may require a 2-ounce portion. To estimate 2 ounces of dried spaghetti, grip the pasta firmly in your fist. If the end of the bunch of pasta measures about 3/8 inch across -- about the size as a nickel -- you have 2 ounces or two portions. If you only need one 1-ounce serving size, use a dime to measure the pasta.
A single ½-cup portion of cooked pasta is about the size of half of an adult fist. For larger portions or when cooking for two, the amount of pasta should be similar in size to a full adult fist. You can also use a dry measuring cup to accurately measure out the servings in ½-cup portions for standard servings or 1-cup portions for larger servings.