chi [Chinese. 尺]

In China since 1959, a unit of length in the market system (shì zhì), = ¹/₃ meter. (UN 1966) Usually romanized as chi before the official adoption of pin–yin romanization by the People’s Republic of China, but also as che, chih, ch’ih and even techi. For current values in Taiwan, see ch'ih. Traditionally it is the length of a type of flute, and is also 90 wheat grains long.

In the customs treaties forced on the Chinese by the European powers in the middle of the 19th century, for the purposes of Canton customs the chih was defined as 14.1 inches (about 35.81 centimeters), but this value was not used elsewhere. Observers noted these values:

12.3 and 12.5 inches for public works
12.4 inches in statistics
12.6 inches for architects
12.7 inches, the common che
13.1 tribunal of mathematics

In Shanghai, the Board of Revenue used a 13.2 inch che.

A reform early in the 20^th century made the che 0.32 meter (12.598 inches). Nevertheless, an official survey in 1936 found 53 values for the che, varying from 0.2 to 1.25 meters, both by locality and by trade.

Scholars have suggested the following values for earlier times.

Dynasty	Dates	Value of che in centimeters
Huang–ti	After 2697 bce	24.88
Yü	2254–2204 bce	24.88
Hsia	2204–1765 bce	24.88
Shang	1765–1121 bce	31.10
Chou	1121–220 bce	19.91
Ch'in	349–205 bce	27.65
Former Han	205 bce – 8 ce	27.65
Hsin Mang	9–24 ce	23.04
Later Han	25–220 ce	23.04
Wei	220–265 ce	24.12
Western Tsin	265–273 ce	24.12
	274–316	23.04
Eastern Tsin	317–430	24.45
Former Chao	318–319	24.19
Liu–Sung	420–478	24.51
South Ch'i	479–501	24.51
Liang & Chen	502–588	24.51
Liang	502–557	23.20 (new legal ruler)
		23.55 (sundial measuring ruler)
Chen	557–588	23.55
Later Wei & West Wei	386–557	29.51
Later Wei & East Wei	495–550	29.97
North Ch'i	550–557	29.97
North Chou	557–566	29.51 (market ruler)
	566–581	26.68 (jade ruler)
	577–581	24.51 (iron ruler)
Sui	581–606	29.51
Sui	607–618	23.55
T'ang	618–906	31.10
Five Dynasties	907–960	31.10
Sung	960–1279	30.72
Yuan	1279–1368	30.72
Ming	1368–1644	31.10
Ch'ing	1644–1911	32.00