Shaku (unit)

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search
Unit systemJapanese units
Unit oflength
1 尺 in ...... is equal to ...
   SI units   0.3030 m
   imperial/US units   0.9942 ft
11.93 in

Shaku (Japanese: ) or Japanese foot[1][2] is a Japanese unit of length derived (but varying) from the Chinese chi, originally based upon the distance measured by a human hand from the tip of the thumb to the tip of the forefinger[3] (compare span). Traditionally, the length varied by location or use, but it is now standardized as 10/33 meters (30.3 centimeters or 11.9 inches).

Etymology in English[edit]

Shaku entered English in the early 18th century,[4] a romanization of the Japanese Go-on reading of the character for Japanese foot (, shaku).

Use in Japan[edit]

The shaku had been standardized as 10/33 meter (30.3 centimeters or 11.9 inches) since 1891.[5] This means that there are 3.3 shaku to one meter.[6][7] The use of the unit for official purposes was banned on March 31, 1966, although it is still used in traditional Japanese carpentry and some other fields. The traditional Japanese bamboo flute known as the shakuhachi ("shaku and eight") derives its name from its length of one shaku and eight sun.[8] Similarly, the koku remains in use in the Japanese lumber trade.

In Japanese media parlance, shaku refers to screen time, i.e. the amount of time someone or something is shown on screen (compare English footage).[9]


Traditionally, the measurement varied over time, location, and use. By the early 19th century they were largely within the range of 0.30175 to 0.303 meters (11.880 in to 11.929 in),[1] but a longer value of the shaku (also known as the kōrai-shaku) was 1.17 times longer than the present value (35.5 centimeters or 14.0 inches).[7][2]

Carpenter's unit and tailor's unit[edit]

Another shaku variant used for measuring cloth, which was 125/330 meters (37.9 centimeters or 14.9 inches). It was called the "whale shaku" (鯨尺, kujirajaku), because baleen (whale whiskers) were used as cloth rulers.

To distinguish the two variants of shaku, the general unit was known as the "metal shaku" (金尺/曲尺, kanejaku).[6] The Shōsōin in Nara preserves some antique ivory one-shaku rulers, known as the kōgebachiru-no-shaku (紅牙撥鏤尺).[10][11]

Derived units[edit]


Just as with the Chinese unit, the shaku is divided into ten smaller units, known as sun () in Japanese, and ten shaku together form a larger unit known in Japanese as a (). The Japanese also had a third derived unit, the ken, equal to 6 shaku; this was used extensively in traditional Japanese architecture as the distance between supporting pillars in Buddhist temples and Shinto shrines.[2]


Ten cubic shaku comprised a koku, reckoned as the amount of rice necessary to sustain a peasant for a year.

Outside Japan[edit]

This Japanese ex-official shaku also forms the basis of the modern Taiwanese foot.

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 Hoffmann, Johann Joseph (1876), A Japanese Grammar, Volume 6 of Classica Japonica facsimile series. Linguistics (2, reprint ed.), E. J. Brill, pp. 166–167
  2. ^ a b c Heino Engel (1985). Measure and construction of the Japanese house. Tuttle Publishing. p. 22. ISBN 978-0-8048-1492-8.
  3. ^ 説文解字 No.5398 「尺、所以指尺䂓榘事也。」 East Asian custom usually considers a span from thumb to index finger rather than from thumb to little finger.
  4. ^ Oxford English Dictionary, Volume XV page 148Webster's Third New International Dictionary of the English Language, 1986
  5. ^ Japanese Metric Changeover Archived 1999-02-21 at the Wayback Machine by Joseph B. Reid, President Emeritus, Canadian Metric Association (U.S. Metric Association page)
  6. ^ a b Details of the two shaku units at
  7. ^ a b "尺" [Shaku]. Nihon Kokugo Daijiten (in Japanese). Tokyo: Shogakukan. 2012. OCLC 56431036. Archived from the original on 2007-08-25. Retrieved 2012-10-29.
  8. ^ A note on shakuhachi lengths
  9. ^ Glossary (Japanese) ESP Entertainment school
  10. ^
  11. ^ Archived 2010-10-18 at the Wayback Machine