To calculate the weight of the fabric, calculate the square yardage of your fabric and divide that into the weight of the fabric.
Your 8 yards is 288 inches long. If the fabric is 62 inches wide that is a total of 17,856 square inches. There are 1296 square inches in a yard. Therefor you have 13.77 square yards. Divide that into the number of ounces you have in the fabric.