What Are Tatami Mats? A Guide to Japanese Flooring

A Japanese room is sized by counting its floor mats, so a space is described as six mats or eight. The mats are tatami, woven from igusa rush over a firm core and bound with cloth along the long edges.

The mat itself is not one fixed size. Japan uses four regional standards, running from 850 x 1700 mm in postwar apartment blocks up to 955 x 1910 mm in Kyoto (Ushiro Tatami, 2026).

Washitsu and tea rooms are the usual places to find them, though temple halls are floored with tatami as well. Whatever the standard, a mat keeps a 2:1 length-to-width ratio, so mats tile a floor with no gaps.

Because the mat sets the size of every room, our guide to Japanese interior design ideas gives it a section of its own.

What Are Tatami Mats?

The floor sets the dimensions in a tatami room, and rooms are named for the number of mats they hold. Each mat is woven soft rush (igusa) over a firm core, with cloth binding the long edges.

Two mats side by side make a square, since a full mat is twice as long as it is wide. That is why a floor of them tiles without gaps.

Floor a room wall to wall with the mats and you have a Japanese-style room, called a washitsu. Sliding doors instead of hinged ones usually come with it.

People often mix tatami up with other things. Goza is the closest relative, a woven rush mat with the same kind of weave as a tatami cover but no core under it. A shikibuton sits on top of tatami, because it’s the Japanese mattress. Then there are the tatami-style foam mats, martial arts flooring that imitates the textured surface of a woven mat.

Century Mats, a martial arts flooring supplier, notes that even in Japan real tatami is less common in dojos. The mats sold for dojo use copy the texture instead.

How Did Tatami Mats Develop in Japan?

The word tatami appears in the Kojiki, compiled in 712, during the Nara period (710 to 794). Palace floors in the Heian period (794 to 1185) were still wooden, and a mat went down only where a high-ranking person sat or slept.

By the Muromachi period (1336 to 1573), shoin-zukuri houses for samurai and priests laid mats wall to wall, starting with small rooms. The mats then reached townspeople’s homes in the Edo period (1603 to 1868), and the regional size standards took shape around the same time.

After that, the mat dictated the room. The Shoin entry on Wikipedia says shoin floor plans were drawn to the mat’s proportions, and those proportions then set door proportions and room height.

The same style came with a tokonoma alcove and built-in shelving. It also brought sliding shoji screens, which sit alongside fusuma doors, as the Japanese housing firm X-House describes it.

The cloth border told people where you ranked. Japanese references such as Kotobank give the multicolored ungen-beri pattern to the emperor, to gods and Buddhas, and to the highest court ranks. Imperial princes and ministers got large-pattern borders. According to a Cocoro guide from 2025, commoners were limited to plain or hemp borders.

It took a while for the mat to settle into the traditional Japanese home. The tatami maker f-tokyo dates townspeople’s adoption to after the middle of the Edo period, and rural homes came later still, after the Meiji era.

How Old Is Tatami, Really?

Retailer guides can’t agree on this one. Hullo says over 1,200 years, while Century Mats goes with almost 2,000.

Only one date is tied to a text. The Kojiki (712) has the oldest written mention of the word, and the Kumamoto tourism guide gives about 1,300 years, so that’s the number I’d use.

The word comes from tatamu, to fold or pile, which suits a movable mat more than a fitted floor.

What Is a Tatami Mat Made Of?

The woven rush cover is the omote and the cloth along the edges is the heri. Between them sits the core, the doko, which makes up most of the thickness and decides how the mat behaves.

Rush and straw are both plant fibers, so tatami fits in with the natural materials Japanese interiors are built from.

Omote, Doko and Heri

The omote is soft rush woven on a hemp or cotton warp, at about 5,000 rush strands per mat, each stretched to roughly 160 cm (Matsuba Tatami). Other makers cite 4,000 to 8,000 strands per mat and rush lengths of 100 to 150 cm, so treat these numbers as approximate.

Most of a mat’s thickness comes from the doko core, and most mats land at 5 to 6 cm thick overall (Web Japan, 2023). The heri is brocade or plain cloth on the long sides. Ryukyu mats skip it entirely. They are square at 88 x 88 cm and have no heri at all (Rakuten Travel).

Rush from Yatsushiro, Hikawa, Uki and Asagiri in Kumamoto Prefecture accounts for about 90% of national tatami production, according to the Japan GI registry entry for Kumamoto Kensan Igusa Tatami-omote (protected 2016).

Historically the big growing areas were Bingo and Bitchu, which are today’s Hiroshima and Okayama. Okayama still led national output around the 1960s, but Kumamoto dominates now.

Rice Straw, Wood Chip and Foam Cores

Rice straw was the traditional core. Modern mats usually have wood chip board or polystyrene foam instead. Foam composites showed up around 1963 and insulation board around 1973 (Modern Japan Crafts, 2026).

The weights are from the manufacturer Daiken’s product data, and the behavior ratings are from Modern Japan Crafts.

Straw is where the sources disagree. Modern Japan Crafts rates it excellent at absorbing and releasing moisture. Ushiro Tatami, a Wakayama maker, says straw in the wrong climate just holds damp, and damp straw is where mold and insects start.

Both can be true. The same property helps where the climate swings between wet and dry, and hurts where it stays wet. Ushiro Tatami exports only insulation-board mats and keeps straw for Japan.

How Big Is a Tatami Mat, and What Is a Jo?

It depends on where you are. A mat measures 880 x 1760 mm in the Tokyo area and 955 x 1910 mm in Kyoto, and a jo is the floor area of one mat. Japan doesn’t have a single mat size, as the table shows.

Sizes come from the Wakayama maker Ushiro Tatami (2026), and the area column is calculated from those dimensions.

Why the Standards Differ

All the sizes trace back to the shaku, the traditional Japanese foot, which is 10/33 of a meter or about 30.3 cm (Akiya Japan, 2026).

Kyoto carpenters did it one way: lay out the mats first, then set the posts around them. This Muromachi-period method is called tatami-wari. Kanto went the other direction and fitted the mats to the distance between pillars, per Rakuten Travel’s tatami guide.

The newest standard, Danchima, was made for the public housing blocks (danchi) of the postwar housing boom. The Japan Housing Corporation behind those blocks was founded in 1955, and the heaviest danchi building ran from the 1950s through the 1970s.

What a Jo Measures

Jo count and mat count are the same number, so “six jo” and “six mats” mean the same thing. What changes is the floor area, which depends on the standard.

Take six mats in Kyoma, which is 6 x 1.824 = 10.94 m2. In Chukyoma the same six mats come to 6 x 1.656 = 9.94 m2, and in Edoma 6 x 1.549 = 9.29 m2. Danchima is the smallest at 6 x 1.445 = 8.67 m2.

Be careful with online converters. Muxtly’s tatami area calculator, for one, assigns 1.62 m2 to an Edoma jo, but multiplying the mat’s own dimensions gives 1.55 m2. Check which value a listing or calculator uses before trusting its square meters.

Every mat keeps a 2:1 proportion, length to width (Japan Architecture). Across the standards in use (Kyoma, Chukyoma, Edoma and Danchima), one jo covers 1.45 to 1.82 m2, so a six-mat room runs from 8.67 to 10.94 m2, a 26% spread from smallest to largest. A half mat, the hanjo, keeps the full width and has half the length.

How Are Tatami Mats Arranged in a Room?

The usual rule is that four mat corners never meet at one point. That layout is shugi-jiki, the auspicious one, and nearly every tatami room in a Japanese home uses it today.

In shugi-jiki the corners form T shapes and never crosses. Edo-period households kept it separate from the layout used on sad occasions, a straight grid where four corners do meet, called fushugi-jiki. A household would switch a room over to the grid for a funeral, though the custom has nearly died out (Akiya Japan, 2026).

Grids do survive in ryokan dining halls and public venues, where the uniform look and faster service matter, as Urchins Home notes.

One Nagoya tatami guide gives the traditional rules. No four corners meet at one point, and no straight line runs across the whole layout, vertically or horizontally. A room gets one half-size mat. On entering, the grain of the mats runs in the direction you walk (Urchins Home).

The Tea Room Size and the Half Mat

The classic tea ceremony room is a 4.5-mat room, yojohan, which holds four full mats and one half mat. Wikipedia’s Chashitsu entry calls 4.5 mats the ideal for modern tea rooms.

Tea rooms range from 1.75 mats (a full mat plus a three-quarter-length daime mat) up to 10 mats or more, while typical private rooms hold 6 or 8.

A tokonoma alcove has a board floor, so it doesn’t count toward the mat total.

How Large Is a Six-Mat Room?

Six mats make a room 3 x 4 mat-widths. Multiply the mat width and you get about 2.87 x 3.82 m in Kyoma and 2.73 x 3.64 m in Chukyoma. Edoma comes to about 2.64 x 3.52 m, and Danchima to about 2.55 x 3.40 m.

These floor dimensions come from multiplying the mat width, and a real room is cut to fit its own set of mats.

How Are Tatami Mats Used in Japanese Homes and Tea Rooms?

People sit, eat, drink tea and sleep on tatami, and the one rule that goes with it is no shoes and no slippers. Bare feet or socks only (Jeepe, 2026).

Visitors leave their slippers at the edge of the room, lined up with the toes pointing out, as More Than Tokyo describes it.

The etiquette goes past footwear. Step over the heri, not on it, and walk around zabuton cushions instead of across them. Luggage gets lifted instead of rolled on casters, and bags and objects stay out of the tokonoma. These come from the etiquette guides of Travel Japan Together and Jeepe, both 2026.

The heri rule has more than one explanation. Travel Japan Together points to the household crests once woven into borders. A plainer reason comes from skdesu, which says it keeps the cloth edge from fraying.

How a Washitsu Is Used Day to Day

Meals and tea happen at a low table (zataku) with zabuton floor cushions, per Jeepe. Long spells in one posture are not comfortable, so Second Home Japan suggests a cushion or a zaisu, the low legless chair, and a regular chair works too.

For sleeping, futon bedding goes down directly on the mats (skdesu, 2026). Many modern Japanese houses keep a single washitsu, and the mats stay down in it rather than being put away (Wikipedia, Bokksu 2025).

Mats in the Tea Room

Tea rooms have a low ceiling and no furniture, which leaves host and guests sitting on the mats in seiza (Wikipedia’s Chashitsu entry).

In the cold season a hearth sunk into the floor is in use, and the mats around it carry the heat of the room.

Which Kind of Tatami Mat Suits a Modern Home?

It comes down to the floor underneath. A room built to the mat grid takes fitted mats, and a wood-floored room does better with loose ones.

The reasoning draws on Interra USA (2024), J-Life and skdesu (2026).

Mats for Wood Floors and Western-Style Rooms

Interra USA traces loose mats to the post-war move from washitsu to Western-style rooms. Traditional mats need a prepared floor base, and adding one to a Western-style house means a costly remodel.

Web Japan (2023) describes mats that sit on top of wooden flooring and cover a single corner or section, which fits the contemporary Japanese style of mixing wood and rush.

Fitted mats follow the mat grid and the jo room count, but they need a prepared floor base. Loose mats go on any floor with no remodel, though they cover only a corner or a section, not a whole floor.

Square Mats, Tatami Art and Synthetic Covers

Borderless square mats are laid in a checkerboard, and designers now use them in modern homes (Travel Japan Together). Tatami art goes further, fitting multi-sided and curved mats together like jigsaw pieces to form images or patterns (Web Japan). Synthetic-fiber covers need less maintenance and come in colors and patterns (Web Japan).

Bed Bases

J-Life describes a Japanese sleep system as a tatami base with a shikifuton on top, and often a kakefuton and pillows too.

The mat sits at the bottom, and its job is airflow.

Judo and Martial Arts Floors

Web Japan says judo matches are always contested on tatami. The floors sold as judo tatami are something else, according to skdesu, which describes thicker foam built differently for a different job.

Both are right, since the word covers a dojo surface and a woven house floor alike.

How Do You Care for Tatami Mats?

Care mostly means humidity control, since moisture is what damages the rush and the core. Beyond that, vacuum along the weave and keep strong sun off the mats.

1. Vacuum along the grain of the weave and skip the heri, which frays easily (Second Home Japan).
2. Wipe with a dry cloth and never pour water on the mat (Maeda Tatami).
3. Ventilate the room regularly, and open windows or run a dehumidifier on humid days.
4. Hang curtains against direct sun, which fades the green (Desinri maintenance checklist).
5. Lift loose mats now and then to air the floor underneath (Comfort Pure).

Ura-gaeshi, Omote-gae and Tatami-gae

Ura-gaeshi means turning the cover over to expose its unused underside, and it only works while the visible surface is still in good condition. Past that point, omote-gae is the next step, where the old cover comes off the core and a new one goes on. Replacing the whole mat is tatami-gae, which is advised when the core itself is damaged (Kyo-tatami, 2026).

Kyo-tatami, a Kyoto tatami shop, schedules ura-gaeshi about 3 to 5 years after installation and omote-gae about 5 years after ura-gaeshi. Core replacement comes at about 20 years.

Not everyone agrees on that last number. A rental-property guide from Ina Group (2026) puts full replacement at 10 to 15 years, because the core deteriorates sooner in rentals.

How much a room is used sets the interval, so heavily used rentals sit at the short end and carefully kept private rooms at the long end.

When Do Tatami Mats Not Work?

Damp rooms are the worst case for tatami. Heavy furniture and strong sun cause trouble too. In any of those rooms, pick another floor or use a loose mat you can lift.

Sustained humidity lets mold and mites move into the weave and the core. Heavy furniture dents the rush, and strong sun bleaches the green cover. Heavy traffic splits and frays the surface, which then needs re-covering (Kobayashi Tatami Kogyo).

Comfort Pure’s care guide targets 40 to 60% relative humidity for tatami. For scale, a study in the Journal of Allergy and Clinical Immunology (Arlian et al., 2001) found that in homes held under 51%, live mites fell from 401 to 8 per gram of dust over 17 months.

The upper end of that tatami range sits above the mite-control level, so in humid summers aim for the lower half.

Maeda Tatami in Morioka tells new-home owners to check their mats weekly, because fresh rush still holds moisture and airtight homes trap humidity.

Furniture with narrow feet puts all its weight on a few spots of the weave. Low furniture that spreads its weight is the better choice, per skdesu, and a kotatsu (a low table with a heat source underneath) is one example.

Where a room cannot be kept dry, lay loose mats you can lift and air instead of a fitted floor.

Tatami Mats FAQ

How much do tatami mats cost?

A new Edoma-size mat starts at about 10,000 yen for an economical grade and goes to 28,000 yen and up for high-class rush (Kinugawa Tatami price list, before tax). Kyo-tatami (2026) lists a mid-grade Kyoto-size mat at 30,000 yen.

Re-covering an existing core is cheaper, from around 5,000 yen.

Is tatami better than carpet?

Neither wins everywhere. Tatami needs airing and periodic renewal, while carpet needs deep cleaning to remove embedded allergens, according to the retailer Tatami Shop (2026).

Humidity matters more than the floor material, since mites follow moisture in either.

Can a tatami mat be used for yoga?

Yes, J-Life lists yoga and stretching among the modern uses of a mat, and the firm woven surface suits floor work.

Just keep sweat and damp towels off the rush, since moisture is what damages it (Maeda Tatami).

Why do tatami mats smell?

Fresh rush smells strongly of grass for a few months after a new mat or cover goes in (Futon Tokyo).

A musty smell is different. It points to damp, so check the humidity and air the room.

Can you flip a tatami mat yourself?

Not in practice. In ura-gaeshi a craftsman detaches the cover from the core and reverses it, then reattaches it with a new heri (Kobayashi Tatami Kogyo).

How to Check a Room Before Buying Tatami Mats

Humidity comes first, because it decides whether tatami lasts in the room at all. Mat size and grade matter only after that, along with the core.

Log the humidity through a full humid season. Pick the core to match that reading, then order mats cut to the room’s own standard.

Treat upkeep as a recurring cost. On Kyo-tatami’s schedule a mat needs a flip by year 5 and a re-cover within about 10 years, so a six-mat room carries at least 30,000 yen of re-covering (6 mats at Kinugawa’s 5,000 yen starting price, before tax).

One downside is that mats are cut to their room, so they don’t move with the owner.

Kinugawa Tatami notes that rush prices shift with climate, so verify any quote at ordering. This position was checked in October 2026.

Furnishing comes next, and decor for a Japanese-style room follows the same low, open approach as the floor.

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Andreea Dima

Andreea Dima is a certified interior designer and the founder of AweDeco, a Bucharest-based interior design studio. Since 2012 she has completed more than 100 residential and commercial projects across Romania and now also offers virtual design consultations for clients abroad. She writes AweDeco’s articles, combining her project experience with manufacturer data and published research.

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