When many people think of show size, they think of just one thing--the number. Yet, this numerical representation only corresponds to the length of the shoe, and not all people's feet are the same width in proportion to the length.
This is where shoe widths come into the picture, represented by letters that come after the numbered size. If you want to measure your shoe width, you don't need the special foot-measuring tool that they have at shoe stores. All you need is something to write with, a ruler and paper.
Put a sheet of paper down on an uncarpeted floor.
Place one of your feet on the sheet.
Draw an outline of the your foot. Keep as close to the sides of your foot as possible.
Use your ruler as a straight edge in order to draw parallel, vertical lines at the widest part on either side of the footprint.
Using your ruler again as a straight edge, draw parallel, horizontal lines at top and bottom of the footprint.
Measure the length of your foot by measuring the distance between the horizontal lines and the width of your foot by measuring the distance between the vertical lines.
Use the length of your foot to figure out your shoe size from a shoe-size chart. This length measurement corresponds to a standard shoe-size number.
Use the width measurement to find out your shoe width from a chart. This will be represented by a letter. Use the right chart for your gender. For women, a AA width is narrow, B is medium and C is wide. For men, C is narrow, D is medium and E is wide.
Sometimes, shoes manufacturers will simply use N for narrow, M for medium and W for wide instead of following the usual shoe-width conventions. Depending on your shoe size, the classification your show width measurement falls into will vary. For example a man with a 4.1-inch width who wears a size 11 shoe has a shoe width of D, or medium, whereas a man with a 4.1-inch width who wears a size 13 shoe has a shoe width of C, or narrow.