You are asking the wrong person - I recently did a small quilt that was supposed to measure 26" square finished - it measured 25 one way and 25.5 the other and it looks just fine - not sure where my problem was, but pretty sure it was all the hourglass blocks because I know the center block was the perfect size because it was applique and I did it on an oversize block and cut it down. I know it is all in the 1/4" seam allowances.