A standard bale of hay has fixed height and width, at 14 inches by 18 inches. The length, however, may vary according to the settings on the baler mechanism and is either 36 inches or 48 inches.
The 36-inch-long bale of hay is bound by two strings and weighs about 45 pounds, while the 48-inch-long bale is bound by three strings and weighs about 60 pounds. Large round bales are produced in a variety of sizes, with the smallest bales 4 feet wide by 4 feet in diameter. The largest balers make bales nearly 8 feet wide by 6 feet in diameter. Round bale weights vary from 500 to 2,500 pounds.