Its been a long time since I took algebra, but this is one of those occasions when I need the right formula to find "X".

I'm trying to find out how many ounces / yard*(squared). of some fabrics?

For instance, I have a hammock (hemmed) cloth of known length and width in inches.
I also have the weight in ounces.
I can measure the hems to adjust for that variable and add those few inches.
Is there a formula or maybe a table that you know of?