Tatami - Size

Size

The size of tatami differs between different regions in Japan. In the Kyoto area, tatami generally measure .955m by 1.91m. Tatami of this size are referred to as Kyōma tatami. Tatami in the Nagoya region generally measure .91m by 1.82m, and are referred to as ainoma (lit., "in-between" size) tatami. In the region around Tokyo, tatami generally measure .88m by 1.76m. Tatami of this size are referred to as Edoma or Kantōma tatami. In terms of thickness, 5.5cm is average for a Kyōma tatami, while 6.0cm is the norm for a Kantōma tatami. A half mat is called a hanjō, and a mat of three-quarter length, which is used in tea-ceremony rooms (chashitsu), is called daimedatami. In terms of traditional Japanese length units, a tatami is (allowing for regional variation) 1 ken by half a ken, or equivalently 6 shaku by 3 shaku – formally this is 1.81818... meters × .90909... meters, the size of Nagoya tatami. Note that a shaku is almost the same length as one foot in the English measurement system.

In Japan, the size of a room is typically measured by the number of tatami mats (-畳 -jō), about 1.653 square meters (for a standard (Nagoya) size tatami). Alternatively, in terms of traditional Japanese area units, room area (and especially house floor area) is measured in terms of tsubo, where one tsubo is the area of two tatami mats (a square); formally 1 ken by 1 ken or a 1.81818... meter square, about 3.306 square meters.

Some common room sizes are (in the Nagoya region):

4½ mats = 9 shaku × 9 shaku ≈ 2.73 m × 2.73 m

6 mats = 9 shaku × 12 shaku ≈ 2.73 m × 3.64 m

8 mats = 12 shaku × 12 shaku ≈ 3.64 m × 3.64 m

Shops were traditionally designed to be 5½ mats, and tea rooms are frequently 4½ mats.