Jō (tatami Mat) to Square Kilometers (jō to km²)

1 jō (tatami mat) equals 0.000001652892562 square kilometers (rounded).

1 jō (tatami mat) = 0.000001652892562 square kilometers

How to convert jō (tatami mat) to square kilometers

To convert jō (tatami mat) to square kilometers, multiply the number of jō (tatami mat) by 0.000001652892562. The factor is rounded to 10 significant digits. To go the other way, multiply square kilometers by 605,000.

square kilometers = jō (tatami mat) × 0.000001652892562

Example: 10 jō (tatami mat) = 0.00001652892562 square kilometers.

Approximate value. Standards for the jō (tatami mat) varied by place and period, so this converter uses the most commonly cited value. Treat results as estimates, not exact figures.

About these units

Jō (tatami Mat) (jō)

JapaneseTraditional unit (still used in some regions)Approximate value

Half a tsubo, about 1.653 m², the area of one tatami mat. Mats vary by region from about 1.44 to 1.82 m², and Japanese real-estate rules set a minimum of 1.62 m² per jō in advertisements.

Jō is the counter for tatami, the woven rush floor mats of Japanese rooms, and the word tatami comes from a verb meaning to fold or pile, since early mats were thin enough to be stacked away. Tatami began as seating for the aristocracy in the Heian period and covered whole rooms in samurai and temple houses by the Muromachi era. They reached ordinary homes only in the late 17th century.

Because a mat was a standard building module, rooms are still described as six jō or eight jō. A mat is about twice as long as it is wide, and size varies by region. Kyoto mats measure about 191 by 95.5 cm, around 1.82 m2, Nagoya mats about 1.65 m2 and Tokyo mats about 1.55 m2. Apartment-block mats can be smaller, near 1.44 m2.

Wikipedia takes the Nagoya mat as the reference, which makes one jō half a tsubo, exactly 200/121 m2 or about 1.653 m2, and that is the figure used here. A separate figure of 1.62 m2 is the minimum area per mat that Japanese property advertising rules allow when a room is described by its mat count, so it is a legal floor rather than a typical mat.

1 jō (tatami mat) = 1.652892562 square meters (approximately).

Sources: Wikipedia: Japanese units of measurement; Wikipedia: Tatami; Real Estate Tokyo: Units used for real estate size in Japan

Square Kilometer (km²)

Metric (SI)Current unit

One million square meters (100 hectares). Used for the area of cities, countries and lakes.

Metric land measure took a surprisingly long time to settle on the kilometer. The meter was defined in 1799, yet people initially preferred the myriameter, 10,000 meters, and the French phrase myriamètres par heure was still in print in 1802. The Netherlands adopted the kilometer in 1817 under the name mijl. Once the kilometer was established, the square kilometer followed naturally as the unit for areas too large to count comfortably in hectares or square meters.

One square kilometer is 1,000,000 square meters, or 100 hectares, about 0.3861 square miles or 247.1 acres. A useful picture comes from history: many medieval European cities were enclosed by walls around roughly a square kilometer, with Delft at about 0.9 km² and Lucca at about 1.09 km². A standard 18-hole golf course of 6,000 meters needs about 0.8 km². The symbol km² means the square of a kilometer, not a thousand square meters. The planned Square Kilometre Array radio telescope takes its name from the collecting area it aims for.

1 square kilometer = 1,000,000 square meters (exactly).

Sources: Wikipedia: Square kilometre; Wikipedia: Kilometres per hour

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