Hat Sizing and Shaping

I'm in the process of knitting a bottom-up hat with some of my handspun yarn. Since I'm not following a pattern, I had to make decisions about the hat dimensions and shaping, and that involved just a little bit of simple math.

Since a lot of knitters are intimidated by the math related to knitting, today I'm going to help you untangle the process of determining how many stitches need to be cast on to create your desired hat circumference, and how to evenly space the decreases at the top of the hat.