The uniqueness of Tilley Hats extends also to their sizing. They have been designed to fit lower and more comfortably than ordinary hats. They are held on by gravity (and the cords when its windy), not painful pressure on your forehead.
Measure above the eyebrows the circumference of your head. Use a flexible tape measure, or use a length of string and measure it against a ruler. Refer to the handy conversion table below to convert head measurements to correct Tilley Hat size.
If you are absolutely certain of your regular hat size, then we recommend you choose one hat size LARGER (i.e., if you wear 73/4, we suggest 77/8)