Tanya Walters in the house of style group on Facebook told me how she made her bonnets because mines are always too small. I made a 35" or so I think. I went 17.5" ( half of 35) all the way around. I got that big booger. I tried 22" and 25" the last one was the winner. I found making the casing a little difficult a lady in the group said she does bias binding and I just happened to have some bias tape and a bias tape foot I have been itching to use!