Pasta Perfection?

Is there some secret formula for measuring uncooked pasta to ensure that a) one doesn't cook too much and b) one doesn't cook too little?

I have always had the problem of cooking too much. "Oh, gee. That doesn't look like nearly enough pasta!" So I'd dump half the economy-sized package in the boiling water, only to end up either a) eating leftover pasta for a week or b) tossing it out the next time the refrigerator was purged.

Tonight I tried very very hard to properly estimate the amount of penne pasta to cook for our dinner. I did not want leftovers. I had a set amount of meat sauce. I wanted to cook just the right amount of noodles to go with the sauce. I carefully read the box. I even pulled out a measuring cup.

"Two ounces equals one serving," I read. Carefully I measured two ounces of dry pasta. Didn't look like much. I needed two servings anyway, so I added another two ounces. Still didn't look like much. So I doubled it to eight ounces. Still didn't look like much, but oh well. The box said two ounces. I was cooking eight. It should be plenty!

So we had an appetizer-sized dinner tonight. The box lied. I am so confused.