Well, the weight of the cloth tells you how much a linear yard of the material weighs. But that's all. There are other factors to consider, other differences between wool and cotton, for example.

Now, I have not seen their cotton in person, but I have seen kilts made out of cotton and even the good looking ones do not look as nice as a comparable weight worsted wool. I'd take a light weight wool kilt over a heavy weight cotton kilt in terms of general appearance.

A 10 or 11 oz worsted wool will make a fine kilt, if you are talking about an eight-yard knife pleated kilt. But I would not use anything lighter than a 13 oz for a four yard kilt, whether knife or box pleated. I've seen them. They look more like skirts, just because the material isn't heavy enough to have a masculine hang to it. It just doesn't look like a kilt. With the deeper pleats and extra cloth of an eight yard kilt, this doesn't make as much of a difference, and a light kilt weight is fine.

I guess what it boils down to is experience. I've seen four yard kilts made from light weight cloth. They look great -- on women. But they just sub-standard when it comes to a man's kilt, and that's why I don't offer them.

(Though if any lady out there wants a box-pleated kilt skirt, I'd be glad to make one for you).
Aye,
Matt