I bought this hat from overseas, but it's too big. I wear a medium (7 1/8"), but this is a large. I measured the inside circumference, which shows 23 1/2 inches. 

Here is a description of the hat:

Handcrafted replica fedora modeled after the iconic hat worn by Harrison Ford as Indiana Jones.

We were contacted many years ago by Indiana Jones fans and hat collectors who wanted an authentic pre-WWII fedora. Hats of this era were generally taller and had fuller crowns than today's hats. Most are sold as "open crown" hats, with pre-creased styles becoming more popular after World War II.

• Felt
• Brim: Dimensional flanged brim
• Ribbon: 1½ inch dark brown vintage galloon ribbon band with screen-accurate Raiders bow style.
• Bash: Hand-shaped Raiders Cairo style.

The size of the hat is based on the circumference of the head. To determine the proper hat size, you must measure your head. Please look closely at the photo showing the hat size and measure your head before bidding!