As far as Japanese homes go, the basic unit in determining their size is in the use of tatami. The tatami is a floor mat. It's made of tightly woven rice straw and is covered with a woven rush, the edges bound with cotton. They are firm and resilient. They can also be replaced relatively easily.
In determining the size of a room, for example, you measure it in tatami. The tatami is 3 feet by 6 feet in size. (although this seems to vary slightly. In Kyoto and in the Kwansi the standard is 37 inches by 77 1/2 inches; in some other places is 37 inches by 71 inches.) It represents the smallest area in which a grown man can sit, work, rest and sleep.
Rooms vary in size from two or three tatami up, with the average room being six, eight or ten tatami in size. Big temples and palaces are measured in the hundreds of tatami.
The size of tatami has varied in another way. During the Heian period the size was determined by the rank of the man who sat on it.
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