How many small square bales of hay in a big square bale?

If by one roll of hay, you actually mean a round bale, it is approximately 40. The actual number depends on the density and size of either bale. With modern equipment becoming ever more impressive, I've heard of some round bales being equivalent to nearly 55 square bales, but when packing round bales to these densities, balers are severely stressed and its operating life is greatly reduced. A better way to figure it out is by weight. A 1100 lb round bale has approx. 17/ 65lb square bales Not all round bales are created equal, you need to ask the weight of the bales then divide the # of square bales at the weight your square bales are.