Cun (unit)

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Chinese name
Korean name
Hangul 촌,치
Japanese name
Hiragana すん
Wooden Ruler.jpg
Wooden ruler of the western Han dynasty, unearthed at Jinguan Pass Site in Jinta County
Unit information
Unit system Chinese unit
Unit of length
Unit conversions
1 cun in ... ... is equal to ...
   metric (SI) units    1/30 m
 ~33.33 mm
   imperial/US units    ~0.10936 ft
 ~1.3123 in
Hong Kong ruler close-up 002.jpg
A section of an old Hong Kong ruler, showing the last (10th) cun of a chi. One can see that the chi in that jurisdiction was exactly equal to 14 5/8 of an inch. A metric ruler is shown next to it for comparison
Unit information
Unit system Chinese unit
Unit of length
Unit conversions
1 tsun in ... ... is equal to ...
   metric (SI) units    0.0371475 m
 ~37.15 mm
   imperial/US units    0.121875 ft
1 37/80 in
Unit system Japanese unit
Unit of length
Unit conversions
1 sun in ... ... is equal to ...
   metric (SI) units    133 m
 ~30.30 mm
   imperial/US units    ~0.099419 ft
 ~1.1930 in

The cun (Chinese: ; pinyin: cùn; Wade–Giles: ts'un; Japanese: sun; Korean: chon), often glossed as the Chinese inch, is a traditional Chinese unit of length. Its traditional measure is the width of a person's thumb at the knuckle, whereas the width of the two forefingers denotes 1.5 cun and the width of all fingers side-by-side is three cuns. In this sense it continues to be used to chart acupuncture points on the human body in various uses of traditional Chinese medicine.

The cun was part of a larger system, and represented one-tenth of a chi ("Chinese foot"). In time the lengths were standardized, although to different values in different jurisdictions. (See chi (unit) for details.)

In Hong Kong, using the traditional standard, it measures ~3.715 cm (~1.463 in) and is written "tsun".[1] In the twentieth century in the Republic of China, the lengths were standardized to fit with the metric system, and in current usage in People's Republic of China and Taiwan[citation needed] it measures 3 13 cm (~1.312 in).

In Japan, the corresponding unit, sun (すん sun?), was standardized at 100033 mm (~3.030 cm, ~1.193 in, or ~0.09942 ft).

See also[edit]


  1. ^ Government of Hong Kong, Weights and Measures Ordinance of 1997

External links[edit]