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Tatami room size calculator
How big is a 6-jō room? Enter the size in tatami mats, square meters, square feet, or tsubo, and see the rest. Mat sizes differ by region, so you can choose the type.
How big is a tatami mat?
There is no single size. A tatami mat is about 1.4 to 1.8 m² depending on the region and the type of building, so the same "6-jō room" can be quite different in size. The difference between the smallest and largest type is about 26%.
| Type | Where it is used | Size | Area (m²) | Area (ft²) |
|---|---|---|---|---|
| Kyoma (Honma) | Kansai area | 1910×955 mm | 1.824 m² | 19.63 ft² |
| Chukyoma | Nagoya area | 1820×910 mm | 1.656 m² | 17.83 ft² |
| Edoma (Kanto) | Tokyo / Kanto area | 1760×880 mm | 1.549 m² | 16.67 ft² |
| Danchima | Apartment blocks | 1700×850 mm | 1.445 m² | 15.55 ft² |
| Real estate listing standard (1.62 m²) | Property listings | — | 1.62 m² | 17.44 ft² |
On floor plans you will see the count written as 畳 or 帖. Both are read "jō" and mean the same thing.
Room size by number of mats
Square meters:
| Mats (jō) | Real estate listing standard (1.62 m²) | Edoma (Kanto) | Chukyoma | Kyoma (Honma) | Danchima |
|---|---|---|---|---|---|
| 4.5 jō | 7.29 m² | 6.97 m² | 7.45 m² | 8.21 m² | 6.5 m² |
| 6 jō | 9.72 m² | 9.29 m² | 9.94 m² | 10.94 m² | 8.67 m² |
| 8 jō | 12.96 m² | 12.39 m² | 13.25 m² | 14.59 m² | 11.56 m² |
| 10 jō | 16.2 m² | 15.49 m² | 16.56 m² | 18.24 m² | 14.45 m² |
| 12 jō | 19.44 m² | 18.59 m² | 19.87 m² | 21.89 m² | 17.34 m² |
| 15 jō | 24.3 m² | 23.23 m² | 24.84 m² | 27.36 m² | 21.67 m² |
Square feet:
| Mats (jō) | Real estate listing standard (1.62 m²) | Edoma (Kanto) | Chukyoma | Kyoma (Honma) | Danchima |
|---|---|---|---|---|---|
| 4.5 jō | 78 ft² | 75 ft² | 80 ft² | 88 ft² | 70 ft² |
| 6 jō | 105 ft² | 100 ft² | 107 ft² | 118 ft² | 93 ft² |
| 8 jō | 140 ft² | 133 ft² | 143 ft² | 157 ft² | 124 ft² |
| 10 jō | 174 ft² | 167 ft² | 178 ft² | 196 ft² | 156 ft² |
| 12 jō | 209 ft² | 200 ft² | 214 ft² | 236 ft² | 187 ft² |
| 15 jō | 262 ft² | 250 ft² | 267 ft² | 295 ft² | 233 ft² |
What the number in a listing means
For apartments and houses for rent or sale, the rules for real estate advertising in Japan say that one jō is counted as 1.62 m² or more. The room's floor area is divided by that figure to get the number of mats shown in the ad. So a "6 jō" room in a listing is at least 9.72 m², even if the room has no tatami at all (many modern rooms have wood or carpet floors).
When you compare rooms, look at the area in square meters on the floor plan, not the number of mats. Square meters are the same for everyone.
What is a tsubo?
A tsubo is a traditional Japanese unit of area, used mostly for land and houses. One tsubo is about 3.3058 m² (400 ÷ 121), the area of a square that is 6 shaku (about 1.82 m) on each side. It is often said that one tsubo equals two tatami mats. That is only a rough guide: depending on the mat type, one tsubo is between about 1.8 and 2.3 mats.
Frequently asked questions
How many square meters is a 6-jō room?
It depends on the mat type. By the real estate standard (1.62 m² per jō) it is at least 9.72 m². With Edoma mats it is about 9.29 m², Chukyoma about 9.94 m², Kyoma about 10.94 m², and Danchima about 8.67 m².
Which mat size should I choose?
If you are reading a rental or sale listing, choose the real estate standard (1.62 m²). If you are buying or ordering actual tatami mats, ask the maker for the exact size, because mats vary by a few centimeters. Edoma is common in Tokyo and the Kanto area, and Kyoma is common in Kyoto and the Kansai area.
How many tatami is 20 m²?
About 12.3 jō by the real estate standard (20 ÷ 1.62). With Edoma mats it is about 12.9 jō, and with Kyoma mats about 11 jō.
How accurate is this calculator?
The tsubo and square meter conversion uses the legal value (1 tsubo = 400/121 m²). The mat sizes are the commonly used dimensions. Real mats differ slightly from house to house.
Sources
- Mat dimensions are the commonly used sizes for Kyoma, Chukyoma, Edoma and Danchima. The conversion between tsubo and square meters is the legal value in Japan. The 1.62 m² per jō figure comes from the fair competition code for real estate advertising.
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Last updated: 2026-10-01