We start with the smallest and easiest sail - the fore royal (the top most square sail).  The Dacron (a Dupoint brand name for polyester) sail cloth comes in 36" widths.  I'm using 4 oz cloth, that means a sailmaker's yard (27" by 36") weighs 4 ounces.  For comparison, I measured my handkerchief - it is about  2.5 oz cloth.   The texture of the sail cloth is very different - more like parchment than regular cloth.  The 36"  width is split into 18" widths.  The fore royal needs 3 of the 18" panels.