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The *Shakkanhō* (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 unit of weight.

This system of units originated in China in the 13th century BC, and stablized in the 10th century BC. The units spread from China to Japan, South East Asia, and Korea. The units were adopted in Japan in 701.

In 1924, the shakkanhō system was replaced by the metric system, and the old units were forbidden for official purposes after 31 March 1966. However, the old system is still used. For example, sake bottles come in sizes which are multiples of the old units. In carpentry, chisels are manufactured in sizes of sun and bu. Bathrooms are built in sizes which are fractions of a tsubo, usually either 3/4, 1, or 1 1/4 of a tsubo, and land is sold on the basis of price in tsubo.

There are several different versions of the shakkanhō. The tables below give the one in common use in the Edo period.

See also the FAQ's length converter.

The basis of length measurements is the shaku. The other units are fractions or multiples of it.

Various different shaku developed for various purposes. The unit
now most widely recognized as a shaku in Japan is the
*kanejaku* (曲尺), shaku, the system shown in the table
below. Kanejaku means "carpenter's square", and this shaku
is the one used by Japanese carpenters.

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 1 1/4 the length of a kanejaku.

As well as the kanejaku and kujirajaku system, various other
shaku systems also exist, for example the
*gofukujaku* (呉服尺),
where gofuku means traditional Japanese clothes, such as
kimonos. In this system, one shaku is 1.2 what it is in the
kanejaku system.

In 1891, the lengths of the two most common shaku were defined in terms of the metric system:

1891 definitions | Kanji | Metric value | Imperial equivalent |
---|---|---|---|

1 kanejaku | 曲尺 | 10/33 m | 11.93 in |

1 kujirajaku | 鯨尺 | 25/66 m | 14.9 in |

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 story
*Issun Bōshi* (一寸法師), literally "one sun boy".

Unit | Kanji | Relative value | Metric value | Imperial value | Notes |
---|---|---|---|---|---|

mō | 毛, 毫 | 1/1000 sun | 0.03030 mm | 0.001193 in | |

rin | 厘 | 1/100 sun | 0.3030 mm | 0.01193 in | |

bu | 分 | 1/10 sun | 3.030 mm | 0.1193 in | |

sun | 寸 | 10 bu, 1/10 shaku | 3.030 cm | 1.193 in | |

shaku | 尺 | 10 sun | 30.30 cm | 11.93 in | |

ken | 間 | 6 shaku | 1.818 m | 71.57 in | |

hiro | 尋 | 6 shaku | 1.818 m | 71.57 in | A unit of depth |

jō | 丈 | 10 shaku | 3.030 m | 119.3 in | |

chō | 町 | 60 ken | 109 m | 358 ft | |

ri | 里 | 36 chō | 3.927 km | 2.44 miles |

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.

See also the FAQ's area converter.

Areas measured in tsubo, the area of two tatami mats, are still commonly used in real estate.

Unit | Kanji | Equivalent value | Metric value | Imperial | Notes |
---|---|---|---|---|---|

1 shaku | 勺 | 1/10 gō | 330.58 cm² | 51.24 in² | |

1 gō | 合 | 1/10 tsubo | 0.33058 m² | 512.4 in² | |

1 tsubo | 坪 | 1 square ken | 3.3058 m² | 35.584 ft² | Used in construction etc. |

1 bu | 歩 | 1 square ken | 3.3058 m² | 35.584 ft² | Used in agriculture. |

1 se | 畝 | 30 tsubo 3,000 go |
99.1736 m² | 1067.50 ft² | |

1 tan | 段, 反 | 10 se | 991.736 m² | 0.2451 acres | |

1 chō or chōbu | 町 | 10 tan | 9,917.36 m² | 2.4506 acres |

See also the FAQ's volume converter.

These units are still used in sake production.

Unit | Kanji | Equivalent value | Metric value | U.S. equivalents | Imperial equivalents | Notes |
---|---|---|---|---|---|---|

shaku | 勺 | 18.039 ml | 0.6100 fluid ounces | 0.6349 fl oz | ||

gō | 合 | 10 shaku | 180.39 ml | 6.100 fl oz | 6.349 fl oz | A common size of serving of sake. |

shō | 升 | 10 gō | 2401/1331 litres (exactly) 1.8039 litres |
61.00 fl oz | 63.49 fl oz | A common size for sake bottles. |

to | 斗 | 10 shō | 18.039 litres | 4.77 gallons | 3.968 gallons | |

koku | 石 | 10 to | 180.39 litres | 40.95 (dry) gallons or 5.12 bushels |
39.68 gallons or 4.96 bushels |
Originally based on the volume of rice eaten by one person in one year |

See also the FAQ's weight converter.

The Japanese unit of weight, momme, is a recognized unit in the international pearl industry. In 1891 1 momme was defined to be 15/4 grams.

Unit | Kanji | Equivalent value | Metric value | Notes |
---|---|---|---|---|

1 fun | 分 | 375 mg | ||

1 momme | 匁 | 10 fun | 3.75 g | |

hyakume | 百目 | 100 momme | 375 g | Hyakume means "100 me" |

1 kin | 斥 | 160 momme | 600 g | |

1 kan or kanme | 貫, 貫目 | 1,000 momme | 3.75 kg |

Apart from shakkanhō and the metric system, inches are used for bicycle tyre sizes, in the electronics industry, and for sizes of television screens, and photographic prints.

Because inches are not a legally recognized unit in Japan, instead of writing the word "inch", Japanese companies substitute "-gata" (型). Thus, a television with a 17 in diagonal measure is described as 17型.

The "kilocalorie" unit, in the form カロリー, is also used, and even has its own symbol, ㌍.

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