JerMc, there are a lot of variables that enter into the formula. My measures are not quite as big as yours, but still required 9 yards of material. (I think my kiltmaker commented that a 45" waist is the break between 8 and 9 yards.) I am having a traditional made from Lamont Ancient tartan, which is a centered tartan. Since the tartan is centered and the finished length was under 25", the kilt could be fashioned from 5 yards of double-width material. Some tartans would have required single-width material, instead.

If you are interested, PM me and I will send you the URL for my kiltmaker.

Peace,
Mike