Ken (間; the unit of length by old Japanese system of weights and measures) (間)

間 (ken, ma, or aida)
(Ken)
The unit of length by old Japanese system of weights and measures. More of this later in this section.

(Ma or aida)
Interval in time or space.
It also means room when it is pronounced 'ma.'

Ken is the unit of length by old Japanese system of weights and measures.

Now in Japan 1 ken is defined to be 6 shaku, and 60 ken is to be cho (町; unit of length; also written as丁). In the Meiji period 1 shaku was fixed as 10 over 33 meters, so 1 ken is equivalent to about 1.8182 meters.

Ken was originally generated in China as the unit of length to measure the interval between pillars. Therefore ken is used to indicate the length of buildings, houses and sites. Jo (1 jo is equivalent to 10 shaku [about 3 meters]) is a unit of similar length, but is used to measure the sizes of objects.

Ken was used as the unit for land survey from around the medieval period in Japan. 1 ken was 6 shaku 3 sun (1.89 meters) during Taiko kenchi (Hideyoshi TOYOTOMI's nationwide land survey) while it was 6 shaku 1 sun (1.83 meters) in the Edo period (however, it varied from area to area). 1 ken was fixed as 6 shaku by the Weights and Measures Act in the Meiji period. In addition, the length of a side of 1 tsubo (or bu; unit of land measurement; 3.31 square meters) area is 1 ken.

Japanese buildings have been designed with 'ken' as a unit. However, it was during the Meiji period that the size of 'ken' was fixed as 6 shaku mentioned previously until then the size of 'ken' had varied from area to area. Even today 'ken' used for designing Japanese houses has two sizes, 'Edoma' (Inakama) used mainly in eastern Japan and 'Kyoma' (Honma) used mainly in western Japan.

Edoma
1 ken is to be 6 shaku (1.8 meters). The size of Tatami mat is 5 shaku 8 sun (1.74 meters) times 2 shaku 9 sun (0.87 meters).

Kyoma
1 ken is to be 6 shaku 5 sun (1.95 meters). The size of Tatami mat is 6 shaku 3 sun (1.89 meters) times 3 shaku 1 sun 5 bu (0.945 meters).

The size of tatami mats which are laid there is to be about 1 ken times 0.5 ken, but in fact the size is smaller than that by the width of pillars because tatami mats are laid between them. The size of tatami mats vary according to the size of 'ken' in which they are laid.