I don't have a scale (I'm working on getting one), and I am not quite sure how much 3 oz of hamburger is in cups. Anyone know?
Grab some with your hand and flatten it into a patty- should be about 3 oz.
Another option is to take the weight that is listed on the package, convert it into ounces and divide by 3.
So 1lb of chop meat should yield about five 3 oz patties.