How do I crochet an adult hat that will fit properly?

I am an intermediate-level crochet-er who has modified patterns. I am trying to crochet a hat for my husband, and am using a pattern for an adult hat. It is a double-crochet spiral pattern. I have gotten about half-way through the pattern twice, have found the hat to be too big, took out stitches, and changed the increase intervals. What I’m hoping for is a way to pre-determine sizing, perhaps based on head circumference. If you know how to do this, please let me know. Thanks!

I have a fool proof skull cap pattern in dc! The way my pattern works is you make a circle in dc a little smaller than the top of your husbands head (crown). then you work one row of sc, next row and all remaining rows dc, working even, no increases. work this until when on his head the edge is about and inch or so below his ear lobes (so you can fold up for a double layer on ears). for the last row work a reverse sc (gives a finished look). The great thing is that this pattern is not dependent on # of sts but simple measurements. You can use any weight yarn, and any size hook, even any st you prefer! Enjoy, any questions e mail…I have many custom patterns, and a large library if you’re looking for something specific.

Stripe Crochet Beanie Cap Hat