What is the normal distribution for clothing sizes?

Answer 1

You can find regulations about clothing sizes in the EN 13402 standard, and a series of physical measurements in the SIRI-dataset.

Reading the standard, I see that t-shirt sizes (men), for example, are mainly based on chest circumferences. Size 'M' is suitable for chest circumferences between 94 and 102 cm. Size S is 8 cm smaller, size L is 8 cm bigger, XL is 16 cm bigger and XS is 16 cm smaller than size M.

When I calculate the median and standard deviation of all the chest circumferences (adult males) I find in the SIRI-dataset, I find a median of 99.6 cm, and - surprise - a standard deviation of 8.4 cm. So, I tend to believe that clothing sizes follow, in some way, the normal distribution.

Size M refers to the median size, and the intervals between the size codes have about the same value as the standard deviation. So, size S is one standard deviation smaller than size M, and XL is two standard deviations bigger than size M.

If haven't checked other types of clothes and other physical sizes, so I cannot guarantee that my conclusion is correct for any type of garment.