Most Birkenstock styles are available in Regular or Narrow Width. The Narrow fits Narrow feet. The Regular fits Regular to Wider width feet. About 80% of the population are suited to the Regular fit. If you already own a pair of Birkenstocks or are trying them on in store - check out the little foot symbol on the footbed of the shoe (between the arch and heel) or on the shoe box. If the foot is coloured in, it is a Narrow (N). If it is just an outline of a foot, it is a Regular (R).