To make these hats I used category 1, super fine (fingering) yarn, and size E/4 (3.5 mm) hook.
The hats turned out super soft and delicate. They measure about 13 inches in circumference, and 4.5 inches in height, which would fit a newborn baby.
To make a bigger size baby hat, use a bigger size hook and heavier yearn.
The skill level for this hat is beginner, and only basic stitches are used - single crochet, double crochet, slip stitch, and chains.
The pattern is very detailed and easy to read/follow. It's available in my Etsy Shop.