tatami

In Japan, a traditional unit measuring the area of a domestic room. The tatami is a woven straw mat used as floor covering; its size became standardized in the Muromachi Period (1338-1573) at one ken long and half a ken wide. The ken, however, has varied. It is approximately 1.82 meters (1.97 in the Kansai area, including the cities of Kyoto, Osaka, and Kobe). Thus 1 tatami is approximately 1.66 square meters.