Sew a Boutique Blanket by The DIY Mommy (plus she tells the measurements for different size blankets--crib, toddler, adult throw) I might need to get out my sewing machine, that's never been out of the box and learn!
DIY swaddle blanket-a yard of jersey knit material and cut it in half along the line that it already had from being on the bolt. The edges just curl up so no need to hem! This makes two very lightweight, stretchy blankets! You could get away with less than a yard if it's for an newborn