Piloncillo is sold by the ounce in a cone shape. You can find small 2 oz cones all the way up to large 8 ounce cones. Piloncillo is sometimes listed in a recipe in pounds, as in "1 pound of Piloncillo" which sounds like a lot, but it is just 2 of the 8 oz. cones.
The measurements for Piloncillo are always in weight. The cones make it easy to measure since they are pre-formed in common weights for recipes. Do not break up the cone and then measure it by the cup (sometimes referred to as 8 ounces) or you will have an inaccurate amount.
Piloncillo means "Pylon" and is named for its conical shape. It is pressed into a cone shape and becomes very hard.