The pasta will weight at least twice as much once cooked (because it has absorbed water).
I have heard "2 ounces dry" = "5 ounces cooked" (or, about 3/4-cup). Though it may vary in cooked weight (depending how much water it absorbs) and cooked volume (small shapes may pack more tightly into the cup than large "fluffy" shapes. Which is probably why they usually give the nutritional information for "dry." Just weigh your portion before you cook it. A little trickier when trying to cook one pot of pasta for two or more people, and you only want to weigh "your" portion... If this is the case, weigh it dry, then weigh or measure the entire thing once cooked - then you can figure out how much to take for "your" serving size.