Size / Head Measurement / Hat Height

Newborn - 3 months / 13-14 inches / 4.5-6 inches = D hook
3-6 months / 14-15 inches / 6-6.25 inches = E hook
6-12 months / 16-17 inches / 6.25-6.5 inches = F hook
Toddler / 18-19 inches / 7.25-7.5 inches = G hook
Child / 19-20 inches / 7.5-8 inches = H hook
Teen / 20.5-22 inches / 7.5-8 inches = I hook
Woman / 21.5-22.5 inches / 8 inches = J hook
Use a smaller hook for a smaller size or a larger hook for a larger hat.

Video Tutorial: https://www.youtube.com/watch?v=CsQwRxtZLIA