Width or girth designators
Some manufacturers offer shoes of different width for the same foot length. Such shoes are then also labelled according to the width or girth of the widest part of the foot (typically measured directly behind the toes with the subject standing on both feet and wearing socks or hose).

In the Mondopoint system, the shoe size label can state in addition to the length also the width of the mean foot for which the shoe is suitable, both measured in millimetres.

A number of other ad-hoc notations for width or girth are also used. Examples include (each starting with the narrowest width):

AAAA, AAA, AA, A, B, C, D, E, EE, EEE, EEEE, EEEEEE
4A, 3A, 2A, A, B, C, D, E, 2E, 3E, 4E, 6E
N, R, W
None of these designations is formally standardized. The exact foot width for which these sizes are suitable can vary significantly between manufacturers. The A-E width indicators used by some US and UK shoe manufacturers are typically based on the width of the foot, and common step sizes are 1/4 inch (6 mm) or 3/16 inch (5 mm).