US standard clothing size

US standard clothing sizes for women were originally developed from statistical data in the 1940s–1950s. At that time, they were similar in concept to the EN 13402 European clothing size standard, although individual manufacturers have always deviated from them, sometimes significantly.

However, as a result of various cultural pressures, most notably vanity sizing, North American clothing sizes have drifted substantially away from this standard over time, and now have very little connection to it. Instead, they now follow the more loosely defined standards known as US catalog sizes.

Body measurements below are given in inches.

Men's standard sizes were probably developed first during the American Revolutionary War, and they were in regular use by the American army during the War of 1812 for ready-made uniforms (Felsenthal 2012). These were based on the chest measurement, with other measurements being assumed to be either proportional (the circumference of the neck, waist, hips, and thighs) or easily altered (length of the inseam) (Felsenthal 2012).

As this was largely successful in men, the same approach was attempted in the early 20th century for women using the bust as the sole measurement (Felsenthal 2012). However, this proved unsuccessful because women's bodies have far more variety in shape. The hourglass figure is frequently used as an industry standard, but only 8% of women have this body shape (Felsenthal 2012). A woman with an hourglass figure and a woman with an apple-shaped figure who have the same bust size will not have the same waist or hip sizes.

This was a significant problem for mail-order companies, and several attempts at predictable, standard sizing were made (Felsenthal 2012). In the 1940s, the statisticians Ruth O'Brien and William Shelton received a Works Progress Administration grant to conduct the most ambitious effort to solve this problem. Their team measured almost 15,000 women across the US. After discovering the complex diversity of women's actual sizes, which produced five to seven different body shapes, they proposed a three-part sizing system. Each size would be the combination of a single number, representing an upper body measurement, plus an indicator for height (short, regular, and long) and an indication for girth (slim, regular, and stout). The various combinations of height and girth resulted in nine different sizes for each numerical upper-body measurement, which was highly impractical for manufacturing (Felsenthal 2012).

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