Tatami: Traditional Japanese Flooring of Igusa and Rice Straw

In most Japanese homes, you can still find a covering and flooring called tatami [畳]. It is a floor of rice straw under a weave of rush grass, used for a long time among the Japanese. What are its advantages? Why do they still keep at least one room like this?

The same English word often gets stuck to gym foam. House tatami is another object: new mats smell like cut grass, start a gray-green, and rooms are still counted in mats instead of square meters.

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What are tatami like?

Tatami has been used as a luxury seating mat long before it covered whole rooms. You still find it in traditional rooms called washitsu (和室).

In martial arts, “tatami” is also the flooring used for training in a dojo and for competition. That competition surface is usually a tougher foam built to look like a house mat, not a rice-straw floor. House tatami is also used for sitting, sleeping, yoga, and quiet rooms; masseurs sometimes recommend a yielding floor, but that is a comfort choice, not a medical claim.

House tatami is covered with rush grass igusa [藺草]. The core is traditionally made of rice straw, but contemporary versions sometimes have compressed wood boards or polystyrene foam cores. A fresh omote has a grassy scent that fades as the weave turns from green toward gold.

The long sides can be bordered in heri [縁] with brocade or plain fabric. A mat has three parts: doko (the core), omote (the woven surface), and the heri (the fabric edge).

What is the size of a tatami?

The tatami is made in standard sizes, twice as long as its width, and the exact measure changes with the region. Export listings often say 90 cm × 180 cm and about 5 cm thick. That 2:1 rectangle is right; the centimeter numbers in Japan are not one single national size.

Tatami has become so common in Japan that it is used as a measure for rooms. Many people, instead of using m², refer to the number of mats — counted in jō [畳] — to convey a sense of size. A 6-mat room and an 8-mat room are everyday phrases in listings.

Name	Where it is common	Approximate size
Kyōma (京間)	Kyoto and western Japan	191 × 95.5 cm, about 5.5 cm thick
Chūkyōma (中京間)	Nagoya, Aichi, Gifu	182 × 91 cm
Edoma (江戸間)	Tokyo, Kantō and farther north	176 × 88 cm, about 6 cm thick

Apartment blocks sometimes use a smaller danchima around 170 × 85 cm. Besides the full mat there is a half mat called hanjō [半畳] and a three-quarter length mat used in tea rooms, called daimedatami [台目畳].

How the mats are laid also has a name. In the usual shūgijiki [祝儀敷き] layout, joints meet in a T. A grid of plus-sign crossings is the old fushūgijiki [不祝儀敷き] pattern, once used for funerals and still avoided in many homes. That is why a 4.5-mat tea room needs a half mat instead of a neat checkerboard.

What does tatami mean?

The Japanese word is tatami [畳]. In some languages a nearby spelling with a final “e” took hold for gym tiles; the house floor is still tatami, with an “i”.

In the West, the same word often means children’s EVA tiles or the foam used in gyms and fighting rings. Straw mats from Japan are easier to find if you search for igusa tatami, not for puzzle foam.

The term comes from the verb tatamu [畳む], “to fold” or “to stack.” Early mats were thin enough to fold away or pile in layers. In the past, tatami could name any foldable covering, including goza and komo. The way the mats are arranged in a room still has its own vocabulary.

History and origin of tatami

The word already appears in the Kojiki (712). During the Heian period, aristocratic shinden-zukuri residences still had wooden floors, and tatami was used as seating for the highest ranks, not as a full floor.

In the Kamakura period the shoin-zukuri style of samurai and temple residences spread. By the Muromachi period, tatami gradually covered whole rooms. A room fully laid with mats came to be called zashiki [座敷], and seating etiquette started to decide the layout.

Before the mid-16th century, the ruling nobility and samurai slept on tatami or fabric mats called goza [茣蓙], while commoners used straw mats or loose straw. The floor reached ordinary houses toward the end of the 17th century.

Today the core is not always compressed rice straw. Wood pulp, polystyrene, or particle board show up in modern doko. The surface is still usually igusa, sometimes paper or synthetic fiber; the heri is cloth and works as both finish and reinforcement.

Houses built in Japan today often have few rooms with tatami, if any. One washitsu is still common. Rooms with tatami and other traditional features are called nihonma or washitsu, “Japanese-style rooms.” You meet them in homes, tea rooms, ryokan, and temple lodgings.

Types of tatami

Besides the traditional floor of a Japanese house, the word can name other mats. Any foldable covering could once be called tatami.

In the West it is better known as the arena for Japanese martial arts such as karate and judo. Those floors are judo tatami (柔道畳): thicker foam, a different construction, and a different job. They borrow the look and the name, not the rice-straw core.

If the room is Western-style, there are yunitto tatami (ユニット畳) and oki tatami (置き畳) that sit like rugs on an existing floor. A new rice-straw and igusa floor is greenish; over time it turns yellow.

There comes a time to replace the woven surface or recycle the old mat. With ordinary care the omote often lasts around five or six years; the core can last longer if it stays dry. Many mats are factory-made today; some workshops still sew them by hand.

Etiquette and care for tatami floors

Do not step on tatami with outdoor shoes, and not with hallway slippers either. Chairs are uncommon; people sit on the floor or on cushions called zabuton. When you move through a washitsu, lift bags instead of rolling wheels, and keep luggage out of the tokonoma alcove.

Most of these rooms have a sliding door. Do not step on the tracks (shikii): it is rude and it damages the rail. Avoid stepping on the heri as well, so the cloth edge does not fray. In a tatami room you sleep on a futon laid on the mats, and you choose low furniture that spreads its weight, such as a kotatsu.

Do not throw water on the floor. Clean with a vacuum or a barely damp cloth, always along the grain of the igusa, never against it. Straw cores hold humidity; they attract dust mites if they stay damp, and mold if a room is left wet and closed. Keep spills blotted, not rubbed. What do you think of this flooring? Leave your opinion and tips in the comments.

Where to buy a tatami

Finding EVA foam is easy. Finding a traditional igusa mat is a different errand. Meditation cushions with a straw base are easier to locate than a full Kyoto-size floor.

Look first at the material and the regional size, not at the word “tatami” alone. Sports shops sell judo foam. Oriental-goods shops and Japanese craftsmen sell house mats, including oki tatami for a Western room. Online listings mix both. Read whether the surface is igusa, washi, or vinyl, whether the core is straw or foam, and whether the centimeters match Kyōma, Edoma, or a 90 × 180 export cut.

If you already have a wooden floor and want one quiet corner, a few oki mats are simpler than rebuilding a washitsu. If you want a full room, measure the space in half-mats and decide the layout before you order, so the joints can meet in a T instead of a plus sign.