What is a Cun? | The Full and Easy Guide to Measuring in TCM

What is a Cun? It is the cornerstone of the Acupuncture Point location method, it’s your body inch.

But what is a ‘body inch’? Glad you asked.

In Traditional Chinese Medicine, many methods are used to locate such points: paying attention to anatomical features and details, measuring by cun, and nowadays, electronic gadgets help us find the location of the Acupuncture points.

In this article, I will explain how the cun system works and guide you through dividing the body segments into cun so you can better locate the acupuncture points.

In Traditional Chinese Medicine, one cun (pronounced tsoon) is equivalent to the person’s thumb breadth and roughly represents 1/75 of that person’s height. This is a measurement system used to locate Acupunctural points more accurately. Its use in medicine was developed by the ancient Chinese doctor Hua Tuo and since then it has become one of the most useful ways to locate acupuncture points.

​What is a Cun?

In Traditional Chinese Medicine, the measuring of the body areas is performed using a method developed by the renowned ancient Chinese doctor Hua Tuo (also known for creating the Five Animals Play). This measuring method used the person’s thumb breadth as a way to calculate the proper distance between two anatomical points to locate the acupuncture point.

This thumb breadth is called a cun which is pronounced tsoon (don’t look at me, it’s their invention) and it is equivalent to roughly 1/75 of the person’s height. I emphasize pronunciation because you will find many written resources using cun and then you will hear TCM doctors say tsoon, so keep this in mind.

The length of the cun depends on the person’s body. All of us have a height of roughly 75 cun because it is a proportional measure using our anatomy.

The cun is also divided into ten smaller parts called fen (this one is pronounced normally).

So: 10 fen = 1 cun

This is necessary to know because many acupuncture points are 3.5 cun from a structure or points like Spleen 1 and Lung 11 are 0.1 cun (1 fen) away from the fingernail.

Another way to measure one cun is using the middle phalanx of the middle finger, the distance between the medial and distal phalangeal joints.

Wanna know something cool?

In Western Medicine, there is also a similar system of measuring body segments using a part of the body, in this case, the fist. It was invented by Leonardo Da Vinci when doing his anatomy studies. That is why painters use the classical thumbs-up gesture when painting. Just like the cun is a proportional measure of the body in the East, the fist is in the West.

Some examples are: Your heart and kidneys are about one fist big, and your lungs and liver are two fists big.

Nowadays as a mean of standardizing and matching it to the metric system, one cun is set to be equal to 3.03cm (1.312 in). This particular case is common in the manufacturing of TCM tools like needles where standard units are needed. When it comes to the body, the classical way is the one used.

​How to Measure the Body Using Cun in TCM

When locating Acupuncture points you will use the cun measurement for more accuracy.

If you are measuring yourself then you will use your hand measures for it. However, when measuring another person you have to compare your hand to the other person’s hand.

Why? Because you have to guide yourself according to the other person’s dimensions, their own cun. Imagine you are locating the acupuncture points of a person who is significantly smaller or taller than you, do you think your measures will match their points’ location?

Take a kid for example, if you want to locate Pericardium 6 which is 2 cun away from the wrist crease and you guide yourself from your dimensions, using your own cun instead of the kid’s, you will find yourself missing the location.

Cun Measurement in the Body

Using this tool, the ancient Chinese doctors began to analyze the different segments of the body and noticed there were some segments with constant distances around every person. For example: in every person the distance between the glabella (the zone between your eyebrows) and the hairline was three thumb breadths.

Using these constant distances between two anatomical regions makes it easier to find the acupuncture points.

Now let’s analyze the equivalences in the body:

​Fingers

These equivalents are used for measuring mostly.

• One thumb breadth is 1 cun.
• The breadth of your index and middle finger is equal to 1.5 cun.
• The breadth of your index, middle, and ring fingers is equal to 2 cun.
• The breadth of your four fingers is equal to 3 cun.

​Head

​Chest and Abdomen

• From the sternal notch to the point of junction between the sternum and the xiphoid process (Ren 16): 9 cun.
• From Ren 16 to the belly button: 9 cun.
• From the belly button to the upper border of the pubic symphysis (Ren 2): 5 cun.
• The distance between the nipples: 8 cun.
• The distance between the outer border of the rectus abdominis muscles (6-pack muscles): 8 cun.

​Arms

• From the front or back armpit fold to the elbow crease: 9 cun.
• From the elbow crease to the wrist fold: 12 cun.
• From the wrist crease to the first fold of the middle finger: 4 cun.

​Legs

Legs have different measures on their inner and outer sides.

Inner side:

• From the superior edge of the pubis to the superior edge of the femur’s condyle: 18 cun.
• From the superior edge of the femur’s interior condyle to the lower edge of the tibial condyle: 3 cun and 5 fen (3.5 cun).
• From the lower edge of the interior tibial condyle to the center of the inner ankle: 13 cun.
• From the center of the inner ankle to the sole: 3 cun.

Outer side

• From the center of the major trochanter to the popliteal crease: 19 cun.
• From the popliteal crease to the center of the outer ankle: 16 cun.
• From the outer ankle to the sole: 3 cun.

Foot: From the heel to the fold of the second toe: 12 cun.

​Final Thoughts

Now that you have learned how the cun measurement method works and the equivalences throughout the body you are in a better place to locate Acupuncture points. Bookmark this post and/or keep returning to it when you need more clarification regarding the different distances.

See you in the next post!