Japanese units of measurement

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Shakkan-hō (尺貫法?) is the traditional Japanese system of measurement. The name shakkanhō originates from the name of two of the units, the shaku, a unit of length, and the kan, a mass measurement.

The system is Chinese in origin. The units originated in the Shang Dynasty in the 13th century BC, and eventually stabilized in the Zhou Dynasty in the 10th century BC and spread from there to Japan, South East Asia, and Korea. The units of the Tang Dynasty were officially adopted in Japan in 701[citation needed], and the current shaku measurement has hardly altered since then. Many Taiwanese units of measurement are derived form the shakkanhō system.

From 1924, the shakkanhō system was replaced by the metric system, and use of the old units for official purposes was forbidden after 31 March 1966. However, in several instances the old system is still used. In carpentry and agriculture use of the old fashioned terms is common. Tools such as Japanese chisels, spatels, saws, hammers are manufactured in sizes of sun and bu. Land is sold on the basis of price in tsubo. The 2005 Japanese census allowed people to give the area of their houses in either square metres or tsubo.

There are several different versions of the shakkanhō. The tables below show the one in common use in the Edo period. In 1891 the most common units were given definitions in terms of the metric system:

1891 definitions
Unit Definition Conversions
Romanized Kanji
Length meters meters inches feet yards
1 jō 丈 100⁄33 3.030  119.3  9.942  3.314 
1 kanejaku 曲尺 10⁄33 0.3030 11.93 0.9942 0.3314
Volume litres litres millilitres US
fluid ounces		 Imperial
fluid ounces
shō 升 2401⁄1331 1.804    1804   61.00    63.49   
Mass grams grams drams ounces pounds
1 momme 匁 15⁄4 3.75  2.116  0.1323  8.267×10-3
Note: Definitions are exact and conversions are rounded to four significant figures.

Contents

[edit] 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 different shaku developed for various purposes. The unit of the base of all measurement, such as area is shaku. To distinguish from other variants of shaku, this unit is called the kanejaku (曲尺?). Kanejaku means "carpenter's square", and this shaku was the one used by Japanese carpenters. The carpenter's shaku, used for construction, preserved the original Chinese shaku measure, because it was never interfered with, whereas the other shaku systems, which were used for taxation or trade, were interfered with in order to increase taxation, and hence gradually varied from the original value[citation needed].

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

As well as the kanejaku and kujirajaku system, various other shaku systems also existed, for example the gofukujaku (呉服尺), where gofuku means traditional Japanese clothes, such as kimonos. In the gofukujaku system, one shaku is equal to 1.2 times the kanejaku's shaku.

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 on in the name of the bamboo flute shakuhachi (尺八?), literally "shaku eight", which is one shaku and eight sun in length, 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?).[1][2]

Table of length units
Unit shaku Metric Imperial/US
Romanized Kanji millimeters meters 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, 1⁄1000, 1⁄100 and 1⁄10, respectively, which are also used as fractional units.
  • The shaku is in some cases Japanese equivalent to the foot.[3]
  • The hiro is a unit of depth—the Japanese equivalent to the fathom.[citation needed]
  • 1 chō = 60 ken ≈ 0.1091 kilometres ≈ 0.06779 miles
  • 1 ri = 36 chō ≈ 3.927 kilometres ≈2.440 miles

[edit] Area

The tsubo, which is essentially the area of two standard sized tatami mats, is still commonly used in discussing land pricing in Japan. The larger units are also commonly used by Japanese farmers for discussing the sizes of fields. These units are ractically equivalent to metric units of area which are for registrations of land, no conversions are needed and coloquially used.

Table of area units
Unit tsubo Metric Imperial/US/Liberia/Myanmar
Romanized Kanji square
metres		 square
inches		 square
feet		 square
yards
1 shaku 勺 1⁄100 0.03306 51.24 0.3558 0.03954
1 gō 合 1⁄10 0.3306  512.4  3.558  0.3954 
1 jō 畳 1⁄2 1.653   2562   17.79   1.979  
1 tsubo 坪 1 3.306   5124   35.58   3.954  
1 bu 歩 1 3.306   5124   35.58   3.954  
1 se 畝 30 99.17    1.537×105 1067     118.6    
1 tan 段, 反 300 991.7     1.537×106 1.067×104 1186     
1 chō[4] 町 町歩 3000 9917      1.537×107 1.067×105 1.186×104
Notes:
  • Conversions to metric, imperial and US customary units are rounded to four significant figures.
  • A jō is the size of one tatami mat—used in quoting room sizes.
  • 1 tsubo = 1 square ken—used in construction.
  • 1 bu = 1 square ken—used in agriculture.
  • 1 tan ≈ 0.09917 hectares ≈ 0.2451 acres
  • 1 chō ≈ 0.9917 hectares ≈ 2.451 acres

[edit] Volume

These units are still used, for example, in sake production.

Table of volume units
Unit shō Metric US liquid measure Imperial
Romanized Kanji millilitres litres fluid ounces pints gallons fluid ounces pint gallons
sai 才 1⁄1000 1.804 1.804×10-3 0.06100 3.812×10-3 4.765×10-4 0.06349 3.174×10-3 3.968×10-4
shaku 勺 1⁄100 18.04  0.01804 0.6100  0.03812 4.765×10-3 0.6349  0.03174 3.968×10-3
gō 合 1⁄10 180.4   0.1804  6.100   0.3812  0.04765 6.349   0.3174  0.03968
shō 升 1 1804    1.804   61.00    3.812   0.4765  63.49    3.174   0.3968 
to 斗 10 1.804×104 18.04    610.0     38.12    4.765   634.9     31.74    3.968  
koku 石 100 1.804×105 180.4     6100      381.2     47.65    6349      317.4     39.68   
Notes:
  • Conversions to metric, imperial and US customary units are rounded to four significant figures.
  • The gō is a common size for serving sake.
  • The shō (about 64.827 cubic sun) is a common sake-bottle size (generally labelled as 1800 ml).
  • The koku (about 40.95 US dry gal) originally was the volume of rice a person would eat in one year.

[edit] Mass

The Japanese unit of mass, momme, is a recognized unit in the international pearl industry.

Table of units of mass
Unit momme Metric Avoirdupois
Romanized Kanji milligrams grams kilograms drams ounces pounds
fun 分 1⁄10 375 0.375 3.75×10-4 0.2116 0.01323 8.267×10-4
momme 匁 1 3750 3.75  3.75×10-3 2.116  0.1323  8.267×10-3
hyakume 百目 100 3.75×105 375    0.375   211.6    13.23    0.8267 
kin 斤 160 6×105 600    0.6     338.6    21.16    1.323  
kan or kanme 貫, 貫目 1000 3.75×106 3750    3.75    2116     132.3     8.267  
Note: Metric values are exact and conversions to avoirdupois units are rounded to four significant figures.

[edit] Money

The names of old money live on in Japanese proverbs such as haya oki wa san mon no toku, literally "Waking early gets you three mon", in other words "Early to bed, early to rise makes a man healthy, wealthy, and wise."

Table of money units
Unit Equivalent to
Romanized Kanji
1 mon 文  
1 hiki   10 mon
1 kanmon 貫文 100 hiki

[edit] Other units

Apart from shakkanhō and the metric system, other units are also commonly used in Japan. The most common unit found is the inch. Inches are used in the following:

  • The tyre sizes of bicycles, which are based on a British system
  • In the computer industry, for the sizes of parts, connectors, and semiconductor wafers.
  • Together with feet, for the width and length of magnetic tape.
  • The size of television screens. However, the word 型 ("-gata") is substituted for インチ ("inch"). Thus, a television with a 17 in diagonal measure is described as 17型.
  • The sizes of photographic prints, though rounded to the nearest millimetre.

[edit] References

  1. ^ 甲
  2. ^ 乙
  3. ^ Ministry of Railway (鉄道省 Tetsudō-shō?) ([大正10]). Japan Railway History (日本鉄道史 Nippon (or Nihon) Tetsudō-shi?) 1 of 3 (上巻 Jōkan?) (in Japanese). [Ministry of Railway], p. 49.  "In 10th month of Meiji 3, (probably November 1871) we defined 1 English foot of railway as 1 shaku 4 rin (1.004 shaku) of ours."
  4. ^ "Chōbu" is used when no fraction follows

[edit] External links

[edit] See also

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