What are the old Japanese units like shaku?

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.

Length

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
毛, 毫 1/1000 sun 0.03030 mm 0.001193 in
rin 1/100 sun 0.3030 mm 0.01193 in
bu 1/10 sun 3.030 mm 0.1193 in
sun 10 bu, 1/10 shaku 3.030 cm 1.193 in
shaku 10 sun 30.30 cm 11.93 in
ken 6 shaku 1.818 m 71.57 in
hiro 6 shaku 1.818 m 71.57 in A unit of depth
10 shaku 3.030 m 119.3 in
chō 60 ken 109 m 358 ft
ri 36 chō 3.927 km 2.44 miles

The smallest units, , rin, and bu, are actually the names of fractions, 1/1000, 1/100, and 1/10, respectively, which are also used as fractional units.

Area

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 1/10 gō 330.58 cm² 51.24 in²
1 1/10 tsubo 0.33058 m² 512.4 in²
1 tsubo 1 square ken 3.3058 m² 35.584 ft² Used in construction etc.
1 bu 1 square ken 3.3058 m² 35.584 ft² Used in agriculture.
1 se 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 10 tan 9,917.36 m² 2.4506 acres

Volume

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 18.039 ml 0.6100 fluid ounces 0.6349 fl oz
10 shaku 180.39 ml 6.100 fl oz 6.349 fl oz A common size of serving of sake.
shō 10 2401/1331 litres (exactly)
1.8039 litres
61.00 fl oz 63.49 fl oz A common size for sake bottles.
to 10 shō 18.039 litres 4.77 gallons 3.968 gallons
koku 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

Weight

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 375 mg
1 momme 10 fun 3.75 g
hyakume 百目 100 momme 375 g Hyakume means "100 me"
1 kin 160 momme 600 g
1 kan or kanme 貫, 貫目 1,000 momme 3.75 kg

Other units

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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