Shoe size
A shoe size is an indication of the fitting size of a shoe for a person.
There are a number of different shoe-size systems used worldwide. While all of them use a number to indicate the length of the shoe, they differ in exactly what they measure, what unit of measurement they use, and where the size 0 (or 1) is positioned. Some systems also indicate the shoe width, sometimes also as a number, but in many cases by one of more letters. Additionally, some regions use different shoe-size systems for different types of shoes (e.g., men's, women's, children's, sport, or safety shoes).
The length of a foot is commonly defined as the distance between two parallel lines that are perpendicular to the foot and in contact with the most prominent toe and the most prominent part of the heel. Foot length of the foot is measured with the subject standing barefoot and the weight of the body equally distributed on both feet.
The sizes of the left and right feet are often slightly different. In this case, both feet are measured, and purchasers of mass-produced shoes are advised to purchase a shoe size based upon the larger foot because, contrary to the reality of foot sizes, most manufacturers do not sell pairs of shoes in non-matching sizes. Each size of shoe is considered suitable for a small interval of foot lengths. The inner cavity of a shoe must typically be 15–20 mm longer than the foot, but this relation varies between different types of shoes.
A shoe-size system can refer to three characteristic lengths:
All these measures differ substantially from one another for the same shoe.
Sizing systems also differ in what units of measurement they use. This also results in different increments between shoe sizes because usually, only "full" or "half" sizes are made.
The following length units are commonly used today to define shoe-size systems:
The sizing systems also place size 0 (or 1) at different locations:
Some systems also include the width of a foot, but do so in a variety of ways:
The width for which these sizes are suitable can vary significantly between manufacturers. The A–E width indicators used by most American, Canadian, and some British shoe manufacturers are typically based on the width of the foot, and common step sizes are 3⁄16 inch.
The International Standard is ISO 9407:1991, "Shoe sizes—Mondopoint system of sizing and marking", which recommends a shoe-size system known as Mondopoint.
It is based on the mean foot length and width for which the shoe is suitable, measured in millimetres. A shoe size of 280/110 indicates a mean foot length of 280 millimetres (11 in) and width of 110 millimetres (4.3 in).
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