A few notes about this pattern. I wrote to for my head and my knitting style. I have a small head and knit tight. To make the hat bigger go up in needle, knit loser, or use thinker yarn. I choose Bernat Satin for my yarn because it was cheap, machine washable, and was the right color blue. You’ll need Blue, white and black yarn, yardage is going to depend on your gauge but I used less than 150 yards total.
Size will depend on your gauge (unstretched).
Small = 6 stitches per inch, 17 inches around
Medium = 5 stitches per inch, 20 inches around
Large = 5.5 stitches per inch, 22 inches around
If you want to make the hat taller, add more ribbing or more blue rows before or after the windows, or before you start the decreases.
A quick note on the windows. The pattern should say to repeat the window chart 5 times instead of 4. I’ll get the pattern fixed soon. Another option would be to do 4 repeats but you’ll need to add 5 blue stitches on each line of the chart. You could add them at the end of the chart but it’s up to you.