In clothing, clothing size refers to the label sizes used for garments sold off-the-shelf. There are a large number of standard sizing systems around the world for various garments, such as dresses, tops, skirts, and trousers. Made-to-order garments require measurements to be taken, but these do not need to be converted into national standard form.
Before the invention of clothing sizes in the early 1800s, all clothing was made to fit individuals by either tailors or makers of clothing in homes. Then garment makers noticed that the range of human body dimensions was relatively small. Therefore sizes were invented as a crucial, and underappreciated, step in the mass production of garments.
Standard sizes take into account the combinations of body measurements of the general population:
Horizontal torso measurements include the neck circumference, the shoulder width, the bustline measurements – over-bust circumference, the full bust circumference, the bust-point separation, and the under-bust (rib-cage) circumference – the natural waist circumference, the upper hip circumference and the lower hip circumference.
Vertical torso measurements include the back (neck-waist) length, the shoulder-waist length (not the same as the back length, due to the slope of the shoulder), the bust-shoulder length, the bust-waist length, and the two hip-waist lengths.
Sleeve measurements include the under-arm and over-arm lengths, the fore-arm length, the wrist circumference and the biceps circumference.
However, because of the drape and ease of the fabric, not all measurements are required to obtain a well-fitting dress in most styles.
The European Union has produced a standard EN 13402 intended to replace existing standards in the member countries. It is currently in common use for children's clothing, but not yet for adults.
The United Kingdom has an existing standard for women's clothing BS 3666:1982, however this is rarely followed by manufacturers as it defines sizes in terms of hip and bust measurements only within a limited range. This has resulted in variations between manufacturers and a tendency towards vanity sizing.
The standard sizes have not had stable names, however. For example, the dimensions of two size 10 dresses from different companies, or even from the same company, may have grossly different dimensions; and both are almost certainly larger than the size 10 dimensions described in the US standard. Vanity sizing may be partly responsible for this deviation (which began in earnest in the 1980s).
The new European standard EN 13402 seeks to address this problem, since it is an absolute scale and mandatory; there is no mandatory clothing size standard in the U.S. In the US there exists a US standard clothing size. External websites exist to aid conversion between the different systems.