Body measurements: palm measurement method, Japanese woodcut

Woodblock illustration from a work on 'Chinese' medicine by the 18th century Japanese physician Hara Masakatsu, published in 1807 (4th year of the Bunkwa era). The palm measurement method (yi fu fa) is recorded by the prominent Tang physician Sun Simiao in Qianjin yaofang (Prescriptions Worth a Thousand Gold Pieces) (652 CE). Also known as shoufu, it is one of several digit-based measurement techniques used to establish the location of acu-moxa points. In this method, the patient holds all four fingers close together, and the measurement from the middle joint of the little finger to the index finger is taken as 3 cun [Chinese inches] or 1 palm. Using another digit-based measurement technique, the width of the top joint of the thumb is defined as 1 cun.

Illustration of Sun Simiao's use of the width of the top joint of the thumb as the cun unit