Cun (unit)
The Cun ( Chinese 寸 , Pinyin cùn , W.-G. ts'un , as a unit symbol also cun ; inch ) is a traditional Chinese unit of measurement and is defined as 1 ⁄ 10 of a Chinese foot ( Chi ). In the People's Republic of China, the Chi was fixed at ⅓ meters in 1984, and thus the Cun at 1 ⁄ 30 meters (3 ⅓ centimeters).
In Traditional Chinese Medicine , the cun is a relative unit of measurement that is used to locate the puncture points for needle placement in acupuncture . It is different for each person. The width of the thumb at the level of the distal joint usually defines a cun of the patient. The width of the index and middle fingers together correspond to approx. 1.5 cun, the width over the four folded fingers 3 cun. The cun of an average US citizen is around 18.7 millimeters.