well I don't think that I am very good @ making hats, this is from a pattern on-line, but I think it had more to do with printing to scale then actually being off. As it ended up being to short to go all the way around the hat hence the reason it too me sew long to figure it out. This was a struggle but I like the look of it even though I had to add a pc to it to make it fit! I may have to make another if I have the time. What do you think? I have to add hat tape? not sure what that is but I think it just covers the inside where the hat meets the brim?
A hat tape or head band (as opposed to hat band which goes on the outside) makes a hat fit nicely around your head, the hat is usually 1/4 to 1/2 of an inch wider than the circumference of your head, the head band fits. That way the hat itself does not hug your head closely.
It's usually made from grosgrain ribbon, but there is elasticated tape for sale as well. The grosgrain is stretched on one side (either by using an iron or simply by stretching a small piece at a time between your fingers. The wider edge is sewn to the inside of the hat. The circumference of your head will me considerably less when your hair is off, so make it a bit narrower than you think you need.