Authentic Italian pasta dishes require, at most, a quarter cup of red spaghetti sauce per serving, while traditional American versions of spaghetti call for about 1/2 cup of sauce centered on top of the spaghetti. Therefore, anywhere from 2 to 4 ounces of spaghetti sauce for each serving is needed.
Cook at least 2 ounces of dry pasta per person. If a single person will likely eat multiple portions, account for that in both sauce and pasta. The thicker and heartier the sauce, the less pasta is necessary per person. Thinner sauces require more pasta and less sauce, as they coat the pasta more easily than chunky sauces.