See, this is the part that's really frustrating for me, the advice of the so-called "experts". Knit your hat until it covers the crown of your head. What exactly is the crown of your head? They never explain that? Is it the flat part of your head and you're supposed to stop knitting when it covers the top of your head to where it begins to slope? If so, that's way too big anyway. Then there's the PI formula. Take your head measurement and divide it by three. That's where you're supposed to stop. Well, my head is 22 1/2 inches around. I go with the nearest multiple of 3 which is 21. A third of that is 7. I'm supposed to stop knitting after the hat is 7 inches in circumference or 3 1/2 inches from the hole start at the top. That's WAY too big. It's more practical for me to take this PI and subtract 1/2 an inch from that number. That's about right. As for measuring circumference, I lay the hat flat. Measure across the hat and multiply that measurement by 2.
I'm still struggling with the hat sizing thing myself in both knit and crochet. Seems like one size is too small, another too big. The type of yarn you use makes a big difference with sizing. One of these days I'll get it right and not have to work at it so hard.
Welsh corgis are cool.