Due to the overwhelming interest in this hat, I have expanded the pattern to four sizes: baby, child, adult small, and adult large. In addition there have also been some other tweaks including a change to a more traditional gauge for worsted weight yarn. The original pattern is still available in the one size for those of you who liked it, and there is now a second pdf with the new sizes and updated pattern.

Sizes:
baby (child, adult small, adult large)
13in (16in, 18.5in, 21in)
33cm (40cm, 47cm, 53cm)