Jin (mass)

In ancient China, the office of Sima (司馬) was in charge of military affairs. Because the management of military grain and fodder involved frequent weighing, mass units (such as jin and liang) were also called sima jin (司馬斤), sima liang, and so on. The measuring tools used were called sima scales (司馬秤). This is still true in Hong Kong. One sima jin is equal to sixteen sima liang, which is where the idiom "half a jin vs eight liang"^{[b][10][better source needed]} comes from.^[11][12]

The mass of the jin varies between different eras and regions, but its ratio to contemporaneous units is generally unchanged: one jin is equal to sixteen liang, or 1/120 of a dan. Starting from the late Qing dynasty, the jin was also written in English as catty or kan based on the Malay name for the unit.^[14]

Before the Qing dynasty, various regions and industries in China had their own weight standards for jin and liang. During the Qing, unified weights and measures were implemented. One late-Qing jin was 596.816 g according to the Beiyang government, and equal to 16 liang.^[15]

The jin, or kin, in Taiwan is called the Taiwan jin or taijin (台斤). The taijin is equivalent to the Qing-era Chinese jin. In 1895 Taiwan was ceded to Japan, which implemented the metric system, but Taiwan continued to use the old weights and measures. Thus, after China stopped using the Qing system, it came to be known as the Taiwan system. 1 taijin is 600 grams, or 16 Taiwan liang, and 1 Taiwan liang is equal to 37.5 g.^[23]

Malaysia has similar regulations as Hong Kong, as it was also a former British colony. The rounding is slightly different, a catty (or jin) is 0.604 79 kg.^[5] Similarly, Singapore law stipulates that one catty is also equal to 11⁄3 pounds, or 0.6048 kg.^[6]

In Japan, 1 jin, or kin in Japanese, is equal to 600 grams, but is rarely used. An exception is the jin used for slices of bread. According to the fair competition regulations of the Japanese Bread Fair Trade Council, a jin only needs to be more than 340 g.^[28]

The base unit of Korean mass is the gwan.^[29] At the time of Korea's metrication, however, the geun (or Korean pound) was in more common use. The gwan is usually considered equivalent to 600 g.^[30] The nyang also sees some use among Korean traditional Chinese medicine vendors.^[31]

In Vietnam, the jin is called the cân ta (lit. 'our scale'), and is equal to 604.6 grams. The following table lists common units of mass in Vietnam in the early 20th century:^[37]

Notes:

• The cân ('scale') is also called cân ta ('our scale') to distinguish it from the kilogram (cân tây, 'Western scale').^[39]

The jin, pound and kilogram are all currently used in China. Their meanings and conversions in China are as follows:^[40]

• 市斤 (Chinese jin; lit. 'market jin'): Or simply called jin, also called Chinese pound. In the market system (市制) in use since 1930, 1 jin equals 500 g, equivalent to 1.1023 pounds.^[40]
• 公斤 (kilogram, lit. 'common jin'): A metric unit, equivalent to 1000 g.^[40]
• 磅 (pound): A British Imperial unit, about 453.6 g.

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  Fruit sold in catties in a market in Sanchong, New Taipei, Taiwan
• 
  Tea priced by the catty in Dadaocheng, Taipei, Taiwan
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  A spring scale in Hong Kong with conversions between the metric system (red), traditional Chinese units (green) and Imperial units (in blue)

• Chinese units of measurement
• Japanese units of measurement
• Korean units of measurement
• Taiwanese units of measurement
• Vietnamese units of measurement