It depends on the size on the cup you are talking about and the weight of things in the cup but a cup is not a true measurement like ounces to pounds. You can weigh how many pounds with a balance.
Pounds are weight and cups are volume (size). They are not convertible to each other. Yes, they both use ounces but it is a common mistake to assume that fluid ounces (8 per cup) and regular ounces...