Japanese Units of Measurement - Length

Length

The basis of the shakkanhō length measurements is the shaku, which originated in ancient China. The other units are all fixed fractions or multiples of this basic unit. The shaku was originally the length from the thumb to the middle finger (about 18 cm or 7 in), but its length, and hence the length of the other units, gradually increased, since the length of the unit was related to the level of taxation.

Various shaku developed for various purposes. The unit of all measurement, such as area, is shaku. To distinguish from other shaku, this unit is called the kanejaku (曲尺?). Kanejaku means "carpenter's square", and this shaku was used by Japanese carpenters. The carpenter's shaku, used for construction, preserved the original Chinese shaku measurement, because it was never altered, whereas the other shaku systems, which were used for taxation or trade, were altered to increase taxation, and, hence, gradually deviated from the original value.

The kujirajaku (鯨尺?), literally "whale shaku", was a standard used in the clothing industry. The name, "whale shaku", comes from the rulers, which were made from baleen. A kujirajaku is 25% longer than kanejaku.

As well as the kanejaku and kujirajaku systems, other shaku systems also existed. One example is the gofukujaku (呉服尺), which refers to traditional Japanese clothing, such as kimonos. In the gofukujaku system, one shaku equals 1.2 times the kanejaku.

Shaku units are still used for construction materials in Japan. For example, plywood is usually manufactured in 182 cm × 91 cm (about 72 in × 36 in) sheets known in the trade as saburokuhan (3 × 6版?), or 3 × 6 shaku. Each sheet is about the size of one tatami mat. The thicknesses of the sheets, however, are usually measured in millimetres.

The names of these units also live in the name of the bamboo flute shakuhachi (尺八?), literally "shaku eight", which measures one shaku and eight sun, and the Japanese version of the Tom Thumb story, Issun Bōshi (一寸法師?), literally "one sun boy", as well as in many Japanese proverbs.

The Shōsōin in Nara has ivory one-shaku rulers, the kōgebachiru-no-shaku (紅牙撥鏤尺?).

Table of Lengths
Unit shaku Metric Imperial/US
Romanized Kanji millimetres metres inches feet yards
mō 毛, 毫 1⁄10000 0.03030 3.030×10−5 1.193×10−3 9.942×10−5 3.314×10−5
rin 厘 1⁄1000 0.3030  3.030×10−4 0.01193 9.942×10−4 3.314×10−4
bu 分 1⁄100 3.030   3.030×10−3 0.1193  9.942×10−3 3.314×10−3
sun 寸 1⁄10 30.30    0.03030 1.193  0.09942 0.03314
shaku 尺 1 303.0     0.3030  11.93    0.9942  0.3314 
ken 間 6 1818      1.818   71.58    5.965   1.988  
hiro 尋 6 1818      1.818   71.58    5.965   1.988  
jō 丈 10 3030      3.030   119.3     9.942   3.314  
chō 町 360 1.091×105  109.1     4295      357.9     119.3    
ri 里 12,960 3.927×106  3927      1.546×105 1.288×104 4295     
Notes:
  • Conversions to metric, imperial and US customary units are rounded to four significant figures.
  • The smallest units, mō, rin and bu, are actually the names of fractions, 1⁄10000, 1⁄1000 and 1⁄100, respectively, which are also used as fractional units.
  • The shaku is, in some cases, the Japanese equivalent to the foot.
  • The hiro is a unit of depth—the Japanese equivalent of the fathom.
  • 1 chō = 60 ken ˜ 0.1091 kilometres ˜ 0.06779 miles
  • 1 ri = 36 chō ˜ 3.927 kilometres ˜2.440 miles

Note: There is an older type of 'ri', about 600 m. This can be seen in use, for example, in beach names. Kujukuri Beach is 99 ri (kyu ju ku), about 60 km. Shichiri Beach is 7 ri (shichi) 4.2 km. While this use is evidence of the existence of the 'old' ri, information about it in English is hard to come by.

Read more about this topic:  Japanese Units Of Measurement

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