Jō (tatami Mat) to Square Meters (jō to m²)

1 jō (tatami mat) equals 1.652892562 square meters (rounded).

1 jō (tatami mat) = 1.652892562 square meters

How to convert jō (tatami mat) to square meters

To convert jō (tatami mat) to square meters, multiply the number of jō (tatami mat) by 1.652892562. The factor is rounded to 10 significant digits. To go the other way, multiply square meters by 0.605.

square meters = jō (tatami mat) × 1.652892562

Example: 10 jō (tatami mat) = 16.52892562 square meters.

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 Meter (m²)

Metric (SI)Current unit

The SI unit of area: a square one meter on each side. Used for floor areas and property sizes in most of the world.

Squaring the meter was built into the metric system from the start. The French law of 18 Germinal, Year III (7 April 1795) defined the are, the land unit that gave the hectare its name, as exactly 100 square meters, so the square meter was already the foundation of metric land measure. Nobody is credited with inventing it as a separate unit. It is simply the area of a square one meter on each side, and any SI prefix that works for the meter works for it, with the prefix squared along with the unit.

That squaring catches people out: a square kilometer is one million square meters, not one thousand. Since 1983 the meter has been defined through the speed of light, so the square meter is tied to a constant of nature as well as to the second. A hectare, about the area of Trafalgar Square in London, is 10,000 square meters. In everyday terms one square meter is about 10.76 square feet. Unicode has a compatibility character for it, but the recommended way to write it is the plain superscript two: m².

The square meter is the reference unit for area on this site.

Sources: Wikipedia: Square metre; Wikipedia: Are (unit); NIST: the meter and the SI redefinition

Related conversions

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