I'm not sure if this is correct, by I would assume that whatever your small square measures, you would double for your large square, so 2" finished small square = 4" finished large square. Then, using the rule of thumb for HSTs, you would cut your squares 1" bigger, so for the small HSTs, you would cut your squares 3-1/2" before cutting them in two and cut your large squares 5-1/2" before cutting them apart. You would then have to trim the HSTs down to get your correct size square. This is one that might be easier to paper piece.