Internationally, the size of hay bales varies. Per Measuring Know-How, the most common hay bale dimensions (average) are: Small hay bales: Start at 18 × 35 × 14 inches (46 × 89 × 36 ...

This photo shows the proportion of a large, round Bermuda grass hay bale contained within each of five 6-inch sections. (Photo by Matt Hersom) ...

For example, a 5-foot by 5-foot bale has 98 cubic feet of hay: (5/2)^2 x 3.14 x 5 = ~98. Loosely packed bales have a density of 9 pounds per cubic foot of hay, which equates to 880 pounds of dry feed.