Birkenstock shoes are designed to accommodate all four arches in your foot, providing support and comfort during long periods of wear. Because of the unique Birkenstock design, determining the width you need when buying a pair is essential to ensuring proper support. Unlike other shoes, Birkenstocks don't list their shoes as narrow, regular or wide. They use a picture of a bare foot to demonstrate the width size. Understanding which picture is equivalent is to your width is relatively easy.

Determine your regular shoe width. Unlike shoe length, which is measured in inches, shoe width is designated by letters. Letters AAA, A, B and C are considered narrow-end shoes, with AAA being the most narrow. Letter D is the general width, falling under the regular category when sizing. Letters E, EE and EEE are wide-width shoes, with EEE being the widest.

Look at the box when shopping for Birkenstock sandals and shoes. There will be a picture of a bare foot on the box. If the picture is completely solid, the shoe falls into the narrow category. If the foot is open, the shoes fall into the regular and wide-width category.

Try the Birkenstocks on before buying. Unbuckle all of the buckles and lay your foot down on the foot pad. Make sure your heel rests against the back of the shoe and your toes fall comfortably into the toe bar. Your foot's arch should fit comfortably against the natural arch of the shoe.

Buckle the shoes, making sure they are snug, but not tight. The way Birkenstocks fit will hold the shoe tight against your foot, and may take some getting used to while walking around.

Walk around for a few minutes to make sure your foot fits comfortably into the shoe.