switch to metricJapan joins the global movement

DeChicchis デキキス
1shaku 尺“Japan used the 17.3 cm-long linear measure unit that was common
to all the regions in East Asia for a period of 25,000 years. Under
the inﬂuence of China, the Japanese measuring unit graduallylengthened during the period from the end of the eleventh century
BCE to the middle of the third century BCE. Then, the length of theJapanese measure shaku was stabilized at 23 cm and remained
unchanged until the end of the second century AD. Various civil
disturbances in China had the eﬀect of lengthening the linear
measure substantially to 29 cm until the middle of the seventh
century, and no more signiﬁcant variation has since been observed.”[Iwata S., Weights and Measures in Japan; Encyclopaedia of the History of Science, Technology, and Medicine in Non-Western Cultures, H. Selin (ed),Springer, Dordrecht, 2008. https://doi.org/10.1007/978-1-4020-4425-0̲8935]

2

Traditionally 2畳=1坪
but a tsubo is now
2a standard 3.3 m ,and tatami size varies.
In the inaka-ma method of traditional
Japanese architecture, the standard tatami
ﬂoor mat (which was roughly 6 3 shaku,
or 1 ½ ken) varied slightly to allow
for the thickness of building columns.
In the kyo-ma method, the tatami mat waskept constant at 3.15 6.30 shaku.
3other lengths based on shaku

The hanbō 半棒
is commonly usedin martial arts:
Hanbōjutsu

4

British Imperial
pre-metric standards• The British Imperial
system of weights andmeasures became
commonly usedworldwide in the 18thand 19th Centuries.

• The US standards weresimilar.

5metrification
In 1795, the metric system became official in France, which defined:• the metre (defined as one ten millionth of the distance between theNorth Pole and the Equator through Paris) for length• the are (100 m2) for area [of land]• the stère (1 m3) for volume [of firewood]• the litre (1 dm3) for volume [of liquid]• the gram (defined as being the mass of one cubic centimetre of water)
for mass
The Metric System evolved into the International System ofUnits (abbreviated SI, from the French, Système International)
in 1960. By 2019, all SI units were defined in terms of theseven defining constants: the speed of light in vacuum, thehyperfine transition frequency of caesium, the Planck
constant, the elementary charge, the Boltzmann constant, theAvogadro constant, and the luminous efficacy. From these,
SI defines the meter (m), second (s), kilogram (kg), ampere(A), kelvin (K), mole (mol), and candela (cd), respectively.
6

La Convention du Mètre /The Metre Convention /the Treaty of the Metre
was signed 20 May 1875 in Paris by 17 nations:
Argentina, Austria-Hungary, Belgium, Brazil,Denmark, France, Germany, Italy, Peru, Portugal,Russia, Spain, Sweden and Norway, Switzerland,Ottoman Empire, United States of America, andVenezuela.
The Treaty established the International Bureauof Weights and Measures (BIPM, from Bureau
international des poids et mesures), which is now
an intergovernmental organization with all
diplomatic rights and privileges.

In 1878, the USA approved the Treaty.
In 1884, the UK signed the Treaty,and the prototype kilogram wasdelivered.
In 1893, US customary measurements(inches, feet, pounds, ounces, etc.)
were officially defined in metric terms
by The Mendenhall Order.
7尺貫法 shakkanhō
the “shaku‒kan system”
Japan joined the Convention duMètre in 1885, and the basic units ofthe shaku-kan system were legallydefined in metric terms in 1891.
In 1909, English units (both Imperialand US) also became legal in Japan.
On 1 January 1959, metric units
became the sole legal system inmost areas of Japanese life, although
the shaku-kan and English units
continue to be used.

The gō cup is a traditional Japanese unit equal toshō, ≈180.4 ml since 1891.
The gō is the traditional amount used for a serving of rice and a cup of sake.
However, the 200 ml “Japanese cup” is larger, and the “US cup” is even larger.

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