Japanese units of measurement

Customary Japanese units are a local adaptation of the traditional Chinese system, which was adopted at a very early date. They were imposed and adjusted at various times by local and imperial statutes. The details of the system have varied over time and location in Japan's history. Japan signed the Treaty of the Metre in 1885, with its terms taking effect in 1886. with use of the other systems permitted as a transitional measure. Public education—at the time compulsory through primary school—began to teach the metric system. The Diet revisited the nation's measurements and, with the occupation's approval, promulgated a Measurements Law in June 1951 that reaffirmed its intention to continue Japan's metrication, effective on the first day of 1959. With the majority of the public now exposed to it since childhood, Redrafting of laws to use metric equivalents had already been accomplished, but conversion of the land registries required until 31 March 1966 to complete. Since the original fines for noncompliance were around $140 and governmental agencies mostly preferred to wait for voluntary conversion, metric use by December 1959 was estimated at only 85%. Since research showed that individual Japanese did not intend to actually use the metric units when given other options, however, sale and verification of devices marked with non-metric units (such as rulers and tape measures noting shaku and sun) were criminalised after 1961. Some use of the traditional units continues. Some Japanese describe their weight in terms of kan. Homes continue to be reckoned in terms of tsubo, even on the national census as late as 2005, although the practice was discontinued in 2010. English units continue to be employed in aviation, munitions, and various sports, including golf and baseball. == Length ==

flute, named after its traditional length of 1 shaku and 8 sun'' (54.5 cm) The base unit of Japanese length is the shaku based upon the Chinese chi, with other units derived from it and changing over time based on its dimensions. The chi was originally a span taken from the end of the thumb to the tip of an outstretched middle finger, but which gradually increased in length to about , just a few centimetres longer than the size of a foot. As in China and Korea, Japan employed different shaku for different purposes. The "carpentry" shaku (, kanejaku) was used for construction. It was a little longer in the 19th century prior to its metric redefinition. The "cloth" or 12,960shaku. A still longer unit was formerly standard in Ise on Honshu and throughout the 9 provinces of Kyushu, which comprised 50 chō, 3000 ken, A fourth and shorter ri of about 600m is still evident in some beach names. The "99-Ri" beach at Kujukuri is about 60 km. The "7-Ri" beach at Shichiri is 4.2 km long. The traditional units are still used for construction materials in Japan. For example, plywood is usually manufactured in (about ) sheets known in the trade as , 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 , literally "shaku eight", which measures one shaku and eight sun, and the Japanese version of the Tom Thumb story, , literally "one sun boy", as well as in many Japanese proverbs. == Area ==

The base unit of Japanese area is the tsubo, equivalent to a square ken or 36 square shaku. It is twice the size of the jō, the area of the Nagoya tatami mat. Both units are used informally in discussing real estate floorspace. Due to historical connections, the tsubo is still used as a unit of area in real estate in Taiwan, where it is called the píng. In agricultural contexts, the tsubo is known as the bu. The larger units remain in common use by Japanese farmers when discussing the sizes of fields. == Volume ==

sake cup (1 gō'') for celebrations The base unit of Japanese volume is the shō, although the gō now sees more use since it is reckoned as the appropriate size of a serving of rice or sake. Sake and shochu are both commonly sold in large 1800mL bottles known as , literally "one shō bottle". The koku is historically important: since it was reckoned as the amount of rice necessary to feed a person for a single year, it was used to compute agricultural output and official salaries. The koku of rice was sometimes reckoned as 3000"sacks". By the 1940s the shipping koku was of the shipping ton of 40 or 42cuft (i.e., ); the koku of timber was about 10cuft (); and the koku of fish, like many modern bushels, was no longer reckoned by volume but computed by weight (40kan). The shakujime of timber was about 12cuft () and the taba about 108ft³ ( or ). ==Mass==

The base unit of Japanese mass is the kan, although the momme is more common. It is a recognised unit in the international pearl industry. In English-speaking countries, momme is typically abbreviated as mo. The Japanese form of the Chinese tael was the ryō (). It was customarily reckoned as around 4 or 10 momme but, because of its importance as a fundamental unit of the silver and gold bullion used as currency in medieval Japan, it varied over time and location from those notional values. ==Imperial units==

Imperial units are sometimes used in Japan. Feet and inches are used for most non-sport bicycles, whose tyre sizes follow a British system; for sizes of magnetic tape and many pieces of computer hardware; for photograph sizes; and for the sizes of electronic displays for electronic devices. Photographic prints, however, are usually rounded to the nearest millimetre and screens are not described in terms of inches but "type" (, gata). For instance, a television whose screen has a 17-inch diagonal is described as a "17-type" () and one with a 32-inch widescreen screen is called a "32-vista-type" (). ==See also==