Material plays a large part in the fit of your hat. Leather or straw will not stretch much, whereas cotton has more give to it. Wool is known to shrink. Having a good understanding of what your hat is made of and how it’s constructed will go a long way in terms of how your hat will fit. Measuring your head is another vital step. If you’re in-between sizes, go with the next size up. Never go a size down. You can always add hat tape to your sweatband for the proper fit. Guys in the in-between sizes should have an intimate relationship with these hat size reducers. Your pork pie hat should rest mid-forehead, above the eyebrows, and not obstruct your field of vision. If your hat feels tight or leaves red marks on your head, get a larger size. Your size is correct if you can fit one finger between the hat and your head. No more. No less.