for 2 1/2 in I use two 6 in sqs. For each size larger add 2 in to sqs. Draw an x and sew down both sides of lines 1/4 in.
Cut in half both ways then on lines. Makes 8 HSTs. Just needs a small trim up. I use Quilt In A Days triangle sq up ruler that only needs one cut. Joanns with coupon.