Japanese Room Size Converter (Jo, Tsubo, m², sq ft) — Convert tatami mats (jo), tsubo, square meters and square feet for Japanese apartment listings
Convert the room sizes in Japanese property listings between tatami mats (jo), tsubo, square meters and square feet. Handles the regional mat sizes (kyoma, edoma, danchima) and the 1.62 m² per jo standard used in real-estate ads.
See how big that "6 jo" room or "25 m²" apartment really is, in the units you are used to.
Room Size Converter: tips and things to know
- Japanese property ads count room size in tatami mats (jo, 畳). The industry standard is 1 jo = at least 1.62 m², about 17.4 sq ft.
- A "6 jo" room in Kansai (kyoma mats) is about 1.7 m² larger than a "6 jo" room in Tokyo (edoma mats).
- One tsubo is about 3.3 m² (35.6 sq ft), roughly two tatami mats. Land and house sizes are often quoted in tsubo.
How to use the Room Size Converter
Choose the input unit
Pick square meters, square feet, tsubo, or one of the tatami mat types.
Enter the size
Type the area you want to convert.
Read the result
Every other unit is shown at once, including the property-ad jo figure. Tap a value to copy it.
How Japanese apartment sizes are written
A listing like "1LDK, 35 m²" gives the total floor area in square meters, and the layout code: the number is the count of bedrooms, L is a living room, D a dining area, K a kitchen. "1K" is one room plus a separate kitchen; "1R" is a single room with the kitchen inside it.
Individual rooms are then sized in jo (畳), the number of tatami mats that would fit. A 6-jo room is roughly 10 m² (about 105 sq ft); 4.5 jo, common in older buildings, is about 7 m². Western-style rooms are measured in jo too even though they have no mats.
The total floor area of an apartment is measured to the centre of the walls (hekishin), so the space you can actually use is a little smaller than the figure in the ad.
Tatami mats are not one size
A mat is always twice as long as it is wide, but the actual dimensions vary by region and building type, which is why this tool offers three versions.
- Kyoma (京間), 191 × 95.5 cm, about 1.82 m²: Kansai, Chugoku, Shikoku and Kyushu.
- Edoma (江戸間), 176 × 88 cm, about 1.55 m²: Tokyo, the rest of Kanto, Tohoku and Hokkaido.
- Danchima (団地間), 170 × 85 cm, about 1.45 m²: public housing complexes and many modern apartment blocks.
The 1.62 m² rule in property ads
Because mat sizes differ, the real-estate fair-trade rules require advertisers to use at least 1.62 m² per jo when they describe rooms. The "property ad jo" result in this tool uses that figure, so it is the right one for comparing listings from different agents or regions.
Tsubo, the other unit you will meet
Land, houses and commercial rents are often quoted per tsubo (坪), an old unit equal to two tatami mats or about 3.306 m². Office rent, for instance, is usually stated as yen per tsubo per month.
For a quick estimate, divide square meters by 3.3 to get tsubo, or multiply tsubo by 3.3 to get square meters.
Square feet for comparison
If you think in square feet, one square meter is about 10.76 sq ft. A typical 25 m² Tokyo studio is around 270 sq ft; a 60 m² family apartment is about 645 sq ft. Enter any figure in square feet and the tool converts it to square meters, tsubo and jo at once.
Sources
- Real Estate Fair Trade Council of Japan, fair competition code on real estate representations (不動産の表示に関する公正競争規約)
Room Size Converter FAQ
Why do tatami mats differ in size by region?
Mat sizes grew out of regional building conventions. Kyoma mats in Kansai were sized from the clear space between pillars, while Edoma mats in Kanto were sized from the distance between pillar centres, which makes them smaller.
Is the jo figure in an ad the same as real mats?
No. Ads must use at least 1.62 m² per jo under the fair-trade rules, while real mats are about 1.82 m² (kyoma), 1.55 m² (edoma) or 1.45 m² (danchima).
How do tsubo and square meters relate?
One tsubo is about 3.306 m², or two tatami mats. Divide square meters by 3.306 to get tsubo.
How big is a 6-jo room in square feet?
Using the 1.62 m² ad standard, 6 jo is about 9.7 m², or roughly 105 sq ft. With real edoma mats it is about 9.3 m²; with kyoma mats about 10.9 m².