I measured my foot and ordered according to size chart. I usually wear size 8-8.5 and ordered an 8.5. It was too small so I sent it back and ordered a size 9.  Fits great!  I'm so glad because I love them!  They are exactly what I've been looking for. And I had a hard time finding boots to fit my calves. My calves measure 15.5in around. These boots fit them great!  The shaft circumference measurement is obviously wrong on the description. Another website said they were 15.5in circumference which makes more sense.