The standard we use as kiltmakers is fabric weight is equal to one linear yard of double width fabric.

However, This is not written in stone anywhere and you will see a wide range of ways to calculate fabric weight.

For example - If the fabric is 54" Wide and not 60" the same linear yard will be 10% different. So if they both weigh 13 ounces then the wider fabric is actually lighter.

This problem is aggravated by the weavers who all have their own secret systems and by the fabric sellers who have another secret system.
I have even heard that some man-made fiber kilts are weighed by the diameter of their yarn "As if it were 100% Worsted Wool".

In general though, 11 oz. of your fabric should be 1 yard long by 60" wide.