I knit with two skeins of yarn, a light, minty blue and a white which gives a lovely, motled cloud-like effect. At rest, the hat is about 9 inches in diameter, and stands 6 inches tall. If you want to use just a single yarn, that will work too, but use a worsted weight. For a newborn, use a single strand of sport weight, and shift your needle choices to US 4/6/7 or 5/7/8 depending on guage, and decrease each length measurement in half (ie only continue for 1 inch of stockinette instead of 2 inches as in the pattern).