yeah, i didn't set it up for rectangular quilts. There will always be some variation due to actual vs advertised weight of materials and actual weights of zippers and cords and such. I am trying to help give people an idea of what it will come in at, which is a lot harder when you don't just make 2 sizes of quilts. Try adding 2" to the finished dims as that should account for the seam allowances. I didn't think of that.