How Many Square Metres Is a 6-Tatami Room? | Why Tatami Mat Size Varies by Region, and Jo Explained

How many m² is 6 tatami? The answer for each standard

Going by Japanese rental and sales listings, a 6-tatami room is 9.72 m². That is because the Fair Competition Code on real estate advertising defines one tatami (1 jo) as “1.62 m² or more”, and the tatami counts on floor plans are normally converted at this minimum.

• Property listings (1 jo = 1.62 m²): 6 jo = 9.72 m²
• Kyoma (1 jo = 1.824 m²): 6 jo = 10.94 m²
• Chukyoma (1 jo = 1.656 m²): 6 jo = 9.94 m²
• Edoma (1 jo = 1.549 m²): 6 jo = 9.29 m²
• Danchima (1 jo = 1.445 m²): 6 jo = 8.67 m²

The largest and smallest differ by 2.27 m², about one and a half tatami mats. Put a Kyoma 6-tatami room next to a Danchima one and you can feel the difference, so the impression that “this 6-tatami room is smaller” is not your imagination.

Dimensions of Kyoma, Chukyoma, Edoma and Danchima mats

Tatami sizes are based on the traditional Japanese shaku system of measurement, and different sizes have been used in different regions and types of building. Here are the four main types alongside the listing standard. (1 shaku is about 30.3 cm; 1 sun is a tenth of that, and 1 bu a tenth of a sun.)

Lined up like this, the mats get smaller as you go from west to east. Kyoma rooms were built by fixing the mat size first and placing the columns outside it (“tatami-wari”), while Edoma rooms were built by fixing the column spacing first (“hashira-wari”), so the actual size of a 6-tatami room differs. Danchima, used in apartment buildings, is the smallest, and Japanese-style rooms in condominiums are often close to this size.

What is the difference between 帖 and 畳?

Japanese floor plans use both “6帖” and “6畳”. Both are read “jo” and mean the same unit of area. There are conventions for when each is used.

• 畳: often used for Japanese-style rooms where tatami mats are actually laid, as the character literally means tatami.
• 帖: used for Western-style rooms with wooden flooring or carpet. It was originally a counter for sheets of paper or nori seaweed, so it is not tied to the floor material.
• LDK sizes: since living-dining-kitchen spaces are mostly Western-style, they are usually written with 帖, as in “11.5帖”.

In other words, the character only shows whether the room is Japanese-style; the way the area is calculated does not change. If you see 6帖 and 6畳 side by side, you can compare both as about 9.72 m². Fractions in 0.5 jo steps appear because the figure is worked back from m² and rounded.

Judging furniture layout from the tatami count

Numbers alone make it hard to picture the size, so here are common tatami counts alongside what they are typically used for. The m² figures use the listing standard (1.62 m²).

When planning furniture, thinking in wall lengths rather than tatami counts avoids mistakes. An Edoma 6-tatami room is about 264 × 352 cm and a Danchima one about 255 × 340 cm, so the walkway left beside a 140 cm wide double bed differs by about 10 cm. The depth of beds and sofas matters most on a plan, so note the measured length of the long and short walls at the viewing.

Convert tatami, m² and tsubo all at once

The key to converting tatami counts is to compare while switching between standards. In the area category of the unit converter, you can choose a tatami standard and see m², tsubo and tatami at the same time.

1. 1

   Choose “Area” and pick a tatami standard

   Choose from the property listing standard (1.62 m²), Kyoma, Chukyoma, Edoma and Danchima. Use the property's location and building type to decide.

2. 2

   Enter the tatami count

   Enter 6 and the m², tsubo and other area units for the chosen standard all appear at once.

3. 3

   Switch standards to see the difference

   Even at 6 tatami, Kyoma and Danchima differ by more than 2 m². This helps you judge which standard your measured size is closest to.

4. 4

   Keep a quick reference table

   Copy a table listing 4.5, 6, 8 tatami and so on, and paste it into your viewing notes or comparison list so you can compare rooms at a glance.

Conversions for the traditional units shaku, sun and ken that appear in Japanese room dimensions are covered in the second half of converting inches and centimetres. The same units turn up when measuring closets and curtains. For an example where a 6-tatami room needs 10 m more wallpaper in Kyoma than in Edoma, see how to calculate how much wallpaper you need.

FAQ

How many square metres is a 6-tatami room?

Under the property listing standard (1 jo = 1.62 m²) it is 9.72 m². By mat type, it is 10.94 m² for Kyoma, 9.94 m² for Chukyoma, 9.29 m² for Edoma and 8.67 m² for Danchima. Because the same 6 tatami can differ by up to 2.27 m², check the m² figure on the floor plan or measure the room if you need the exact size. The tatami count is only a guide.

What is the difference between 帖 and 畳?

As units of area they are the same, and both are read “jo”. By convention, 畳 is used for Japanese-style rooms with tatami mats, and 帖 for Western-style rooms with wooden flooring. 帖 was originally a counter for paper and nori seaweed, which is why it can be used regardless of the floor material. When comparing sizes, you can treat 6畳 and 6帖 as the same, about 9.72 m².

How big is one tatami mat in centimetres?

Kyoma is about 191 × 95.5 cm, Chukyoma about 182 × 91 cm, Edoma about 176 × 88 cm and Danchima about 170 × 85 cm. In every case the long side is exactly twice the short side, a shape that shrank region by region from the 6 × 3 shaku Chukyoma. When ordering carpet or replacement tatami, give the measured dimensions rather than just the name.

How do I convert a tatami count to tsubo?

Using the listing standard, tatami count × 1.62 ÷ 3.3058 gives tsubo. As a factor that is about tatami × 0.49, or roughly half. 6 tatami is about 2.9 tsubo, 8 tatami about 3.9 tsubo and 20 tatami about 9.8 tsubo. With Chukyoma mats, 2 tatami is exactly 1 tsubo, so dividing the tatami count by 2 gives tsubo. The standard can shift the result by about 10%, so for detailed comparisons convert to m² first.

Why do 6-tatami rooms differ in size?

Because the size of one tatami mat differs between buildings. Kyoma, centred on the Kansai region, is built by fixing the mat size first and then placing the columns (tatami-wari); Edoma in the Kanto region is built by fixing the column spacing first (hashira-wari); and apartment buildings use the even smaller Danchima. Listings convert at a minimum of 1.62 m² per jo, so rooms with the same listed tatami count do not have the same floor area.