The “cun” measurements

The cun measurement: the acupuncturist's personal measuring scale

In Western medicine, body measurements are expressed in centimetres and millimetres — fixed units that are the same for everyone. In Traditional Chinese Medicine, the approach is fundamentally different: the cun is a personal measurement adapted to the body of the individual patient. This makes the cun one of the most elegant and practical inventions of the Chinese medical tradition.

What is a cun?

The cun (Pinyin: cùn, pronounced "tsun") is a traditional Chinese unit of length that has been used for more than two thousand years to determine the location of acupuncture points. What makes it special is that a cun has no fixed length — it varies from person to person. One cun is equal to the width of the tip of the patient's thumb, or to the width of one finger phalanx. Two fingers placed side by side equal one and a half cun; four fingers side by side equal three cun.

This relative measurement system is precisely what makes it so useful. A tall person of 1.90 m has longer arms and legs than someone of 1.60 m — and therefore larger cun values. But the proportions within the body remain the same: the distance between the kneecap and the ankle is 16 cun in both people, and the distance between the elbow crease and wrist crease is always 12 cun. The cun adapts to the body rather than the other way around.

Fixed cun values on the body

Although the absolute length of a cun varies, the proportions within the body are fixed. Some commonly used reference distances are: the distance from the kneecap to the ankle is 16 cun; from the elbow crease to the wrist crease is 12 cun; from the navel to the pubic bone is 5 cun; the neck is 9 cun; the area between the corners of the forehead is 9 cun. Using these fixed proportions, the acupuncturist can precisely locate every point on every body.

How do you measure in cun?

In practice, the acupuncturist uses fingers as a measuring instrument — but calibrated to the dimensions of the patient, not to the practitioner's own hands. For most clinical applications, three methods are used: the width of the thumb for one cun, the combined width of the index and middle finger for one and a half cun, and the width of four fingers side by side for three cun. It is essential that the acupuncturist has the cun proportions of the body being treated at their fingertips — literally and figuratively.

Practical importance

For the acupuncture student, mastering cun measurements is a fundamental skill that should be practised early in training. Every acupuncture point is described in terms of its distance in cun from anatomical landmarks such as bones, joints and creases. Anyone who masters cun measurements can reliably locate every point on every body — regardless of the patient's height or build.