The two largest sizes are for 20” head and for 22.5” head on US#5 needles. My head measures 21.5”, so I decided on the size L on US#6 needles.
I added three rows for a wider brim.
I followed size Medium for the height of the body of the hat; probably because I was knitting with larger needles which gave me a different gauge per row, but possibly also just because I didn’t want the hat quite that tall. (The pattern gives you gauge per stitch and measurement for head circumference, but not gauge per row or measurement of height).
I also switched to US #5 for the crown shaping.
The hat came out perfectly. I usually wear baseball caps, this one is so much more elegant and I can’t wait to wear it!!! I like this pattern and the yarn goes well with it :)