Tatami Types: What They're Made Of, How They Differ, and How They Measure a Room
Tatami are made from a dense core 畳床, a woven cover 畳表 of igusa grass, and a cloth border 畳縁. Tatami types differ by mat size — from kioma to danchima, by border — with or without a cloth edge, and by core — straw, pressed wood chips, or polystyrene foam. In Japan, room area is counted in tatami: six mats is a standard room, four and a half is a tea room.
Tatami are often confused with futon mattresses, though they are different things: one is laid underfoot all day, the other under your back only at night. Let's look at tatami types by composition and size, why Japanese rooms are traditionally measured in mats rather than square meters, and what happens to tatami in today's apartments.
What Tatami Are Made Of: Core, Cover, and Border
Tatami is a multi-layered mat, not just a woven rug. Inside is a dense core 畳床: it used to be made from compressed rice straw, but now often from pressed wood chips or polystyrene foam. On top is a woven cover 畳表 made of igusa rush grass, and along the long edges a cloth border 畳縁 is sewn on.
Why New Tatami Are Green and Old Ones Are Yellow
A fresh mat smells of grass and has a green sheen — that's the color of freshly cut igusa. Sunlight and air gradually fade and yellow the cover over a few years, and this is natural aging of the material, not a defect.
Tatami Types: By Size, Border, and Filling
By Size: From Kioma to Danchima
Tatami size historically depended on the region — it's a unit of room measurement that varied from place to place, not a product size you choose. Below are approximate values in one set, because different sources differ by a centimeter or two.
| Tatami Type | Size, cm (approx.) | Where Common |
|---|---|---|
| 京間 (kioma) | 191 × 95.5 | Kansai and western Japan |
| 中京間 (chūkyōma) | 182 × 91 | Nagoya and the Tōkai region |
| 江戸間 (edoma) | 176 × 88 | Tokyo and eastern Japan |
| 団地間 (danchima) | 170 × 85 | Apartment buildings and condominiums |
By Border: With a Cloth Edge and Without
Most tatami have a narrow cloth border 畳縁 that covers the seam of the cover, and by custom people try not to step on it. Ryukyu tatami (琉球畳) have no border at all: it's a square mat about half the usual length, laid in a checkerboard pattern — a style that has become popular in modern interiors too.
By Core: Straw, Wood Chips, and Foam
- Straw core — the traditional option made of compressed rice straw, heavy and resilient to the touch.
- Pressed wood chip core — lighter than straw and more common in new construction.
- Polystyrene foam core — the lightest, often combined with wood chips in a single mat.
How Tatami Set Room Size: Jō, Tsubo, and Layout Order
The area of a Japanese room is traditionally counted not in square meters but in the number of mats — jō: 六畳 (roku-jō), a six-tatami room, the standard size of a living room, and 四畳半 (yojō-han), four and a half, the classic size of a tea room. In real estate listings this same unit is sometimes written with the character 帖 instead of 畳 — both are read 'jō' and mean the same thing.
One Tsubo Is Two Tatami
Tsubo (坪) is a unit of land and building area, about 3.31 square meters, and roughly equal to the area of two standard tatami. Hence a handy conversion: the number of tatami in a room divided by two gives the number of tsubo.
Border and Direction: Tatami Layout Customs
The layout of tatami in a room also has a rule: the 'auspicious' layout 祝儀敷き is done so that the joints of the mats never meet in a cross, while in the 'funereal' 不祝儀敷き, on the contrary, the joints are deliberately crossed. This is still how tatami are laid in some temples and large ryokan halls, where the durability of the seam matters more than the superstition.
畳 — The Character That Once Meant 'to Fold'
畳 — значение: tatami, mat, to fold, counter for mats — онъёми: ジョウ、チョウ — кунъёми: たた.む、たたみ、かさ.なる — 12 штрих(ов). 畳 today means both the mat itself and the verb 'to fold': before tatami were laid on the floor entirely, mats were thin underlays that were rolled up and put away during the day.
The character 畳 is read 'jō' in its on'yomi, and in its kun'yomi — 'tatami' and 'tata.mu', 'to fold'. The kinship of meanings is visible in a pair of words: 畳む (tatamu) — 'to fold, to roll up', and 折り畳み (oritatami) — 'folding', from an umbrella to a chair.
To Fold and to Lay Out — The Same Root
The word for a thing you fold and put away, and the word for the floor you then place it on, grow in Japanese from the same character. This is no coincidence: the mat itself was once a folding household item, not part of the architecture of the house.
| Japanese | Reading | Translation |
|---|---|---|
| 畳 | tatami · tatami | Tatami, mat |
| 畳む | tatamu · tatamu | To fold, to roll up |
| 折り畳み | oritatami · oritatami | Folding |
Write 畳 along the guides — the character for tatami, which began as the verb 'to fold'.
FAQ
- What types of tatami are there?
- Tatami differ in three ways: size, border, and core. Size ranges from the large kioma in western Japan to the compact danchima in apartment buildings, and the border is either a cloth edge or none at all, as with square Ryukyu tatami. The core can be straw, pressed wood chips, or polystyrene foam.
- How is tatami different from a futon?
- Tatami is the floor, the mat on which all the room's furniture stands. A futon is bedding that is spread over the tatami at night and put away in the morning. One stays in the room permanently, the other appears and disappears every day.
- Why is a room in Japan measured in tatami rather than square meters?
- The mat itself was a standard building unit: the room module and doorways were fitted to its size. Hence the count in jō — 六畳, six tatami, 四畳半, four and a half — and this count is still clearer to many Japanese than an area in square meters.
- What are tatami made of?
- Tatami consist of three parts: the core 畳床 — formerly straw, now often pressed wood chips or polystyrene foam, the woven cover 畳表 of igusa rush grass, and the cloth border 畳縁 along the long edges of the mat.
- Can you walk on tatami in slippers?
- No: on and around tatami people traditionally walk barefoot or in socks, and shoes and indoor slippers are removed at the genkan or at the room's threshold. The cloth border of the tatami is best not stepped on at all, regardless of footwear.
- Are tatami still laid in today's Japanese apartments?
- Yes, though usually not throughout the whole house: tatami are kept in one or two Japanese-style rooms, while the rest are floored with parquet or carpet. The mat has not disappeared entirely from modern housing, but it has ceased to be the only flooring option.
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Updated: 2026-09-21