Shaku (unit)

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The shaku () is the Japanese version of a traditional unit of measure used in East Asia with a length approximately equal to a foot (at about 11.93 inches). As with other measurements, it was originally derived from nature: the average length between nodes on bamboo. The actual length varies slightly by country.

The shaku may be divided into ten smaller units (寸), known as sun in Japanese. Ten shaku are equal to a , traditionally written as "丈".


The English term shaku[1][2] derives from the Japanese word shaku (?). Early citations indicate that it entered the English language early in the 18th century.[1]


1 shaku (Japan) =
SI units
0.3030 m 303.0 mm
US customary / Imperial units
0.9942 ft 11.93 in

Since 1891,[3] the Japanese shaku ( shaku?) has been defined to equal 10/33 meters (approximately 30.3 cm, or 11.93 inches), or 3.3 shaku to the meter.[4][5] Slightly different, but quite similar values (between 0.30175 and 0.303 m) were given for the shaku by various authorities during the earlier decades of the 19th century.[6]

A single shaku is divided into 10 sun. Smaller, lesser known, fractional units, down to 0.000001 shaku, were known in the past as well.[6]

In the past, a longer value of shaku (known as kōrai-shaku), equal to approximately 1.17 of modern standard shaku, or 35.5 cm (14 inches), was in use.[5][7]

Another unit of length also called the shaku was used only for measuring cloth. This shaku measured 125/330 meters (approximately 37.9 cm, or 14.9 inches). When a distinction needed to be made between the two shaku, the cloth unit was referred to as kujirajaku (whale shaku, as the rulers for measuring cloth were made from whale whiskers) and the other shaku was referred to as kanejaku (metal shaku).[4]

While Japanese law required official use of these units be discontinued on March 31, 1966, the shaku is still used in some fields in Japan, such as the traditional carpentry. The ken and are multiples of a shaku: 6 shaku make up one ken; 10 shaku make up one . The ken is commonly the distance between pillars in traditional buildings such as Buddhist temples and Shinto shrines.[7]

The Shōsōin in Nara has ivory one-shaku rulers, the kōgebachiru-no-shaku (紅牙撥鏤尺?).[8][9]

The shakuhachi is a Japanese bamboo flute whose name (尺八) means "[one] shaku eight [sun]", because, traditionally, its standard length was one shaku and eight sun, i.e. 1.8 shaku.[10]

The shaku is sometimes referred to in English-language works as the "Japanese foot".[6][7]

Derived unit of volume[edit]

Main article: Koku

A koku, defined as 10 cubic shaku, is a traditional unit of volume in Japan. Historically, it was used as a measure of rice, thought as a sufficient amount of food for a man for one year. It is still used in Japanese lumber trade.


1 ja (Korean: ) =
SI units
0.3030 m 303.0 mm
US customary / Imperial units
0.9942 ft 11.93 in

In 1902, the Korean Empire adopted the Japanese definition of the shaku as that of the ja.[citation needed]

See also[edit]


  1. ^ a b Oxford English Dictionary, Volume XV page 148
  2. ^ Webster's Third New International Dictionary of the English Language, 1986
  3. ^ Japanese Metric Changeover by Joseph B. Reid, President Emeritus, Canadian Metric Association (U.S. Metric Association page)
  4. ^ a b Details of the two shaku units at
  5. ^ a b "尺" [Shaku]. Nihon Kokugo Daijiten (in Japanese). Tokyo: Shogakukan. 2012. OCLC 56431036. Retrieved 2012-10-29. 
  6. ^ a b c Hoffmann, Johann Joseph (1876), A Japanese Grammar, Volume 6 of Classica Japonica facsimile series. Linguistics (2, reprint ed.), E. J. Brill, pp. 166–167 
  7. ^ a b c Heino Engel (1985). Measure and construction of the Japanese house. Tuttle Publishing. p. 22. ISBN 978-0-8048-1492-8. 
  8. ^
  9. ^
  10. ^ A note on shakuhachi lengths