How to measure points — the “cun” system
Every location in this app (e.g. “3 cun above the inner ankle”) uses cun — a proportional “body-inch” scaled to each person. It is not a fixed centimetre. Here's how to measure it.
1. Finger-cun (the quick hand method)
The fastest way — use the person's own fingers:
Thumb width = 1 cun
Widest part of the thumb, at the knuckle.
2 fingers = 1.5 cun
Index + middle finger, at the knuckle line.
4 fingers = 3 cun
Index to little finger together, at the knuckles.
Also handy: the length of the middle finger's middle segment (between its two creases when bent) ≈ 1 cun.
2. Body proportions (the precise method)
For accuracy, the body is divided into fixed proportional lengths. Divide the distance between two landmarks into that many equal cun:
| Between these landmarks | = cun |
|---|---|
| Front hairline → back hairline (over the top of the head) | 12 |
| Between the two nipples | 8 |
| Base of the breastbone → centre of the navel | 8 |
| Centre of the navel → top of the pubic bone | 5 |
| Front armpit fold → elbow crease (upper arm) | 9 |
| Elbow crease → wrist crease (forearm) | 12 |
| Top of the pubic bone → top of the kneecap (thigh) | 18 |
| Below the kneecap → tip of the inner ankle bone | 15 |
| Back of the knee crease → tip of the outer ankle bone | 16 |
Worked example
To find SP6 (Sanyinjiao), described as “3 cun above the tip of the inner ankle bone”: place four fingers together (= 3 cun) just above the inner ankle bone — the point sits at the top edge of your fingers, just behind the shinbone. Simple.