how long should my crochet hat be newborn
1 For a newborn hat, the circumference should be 12 to 14 inches (30.5 to 35.5 cm) and the height should be 5.5 to 6 inches (14 to 15 cm). 2  For a 3 to 6 month hat, the circumference should be 14 and 17 inches (35.5 to 43 cm) and the height should be 6.5 to 7 inches (16.5 to 18 cm).