Using Barb's calculations, I'd buy 3.5 yards. It might shrink a little when you launder it before use and you need extra on the ends - I like at least 2 inches (4 inches for 2 ends) , sometimes 3 (6). With a longarm, you might need more. (Remember to double the amount you allow for each end). 3.5 yards = 126". You need 112 + 1 for seam + 6 for ends=119", so 3.5 yards doesn't too allow much for shrinkage.