Tan to Square Miles (tan to mi²)

1 tan equals 0.0003829112316 square miles (rounded).

1 tan = 0.0003829112316 square miles

How to convert tan to square miles

To convert tan to square miles, multiply the number of tan by 0.0003829112316. The factor is rounded to 10 significant digits. To go the other way, multiply square miles by 2,611.571345 (rounded).

square miles = tan × 0.0003829112316

Example: 10 tan = 0.003829112316 square miles.

About these units

Tan (tan)

JapaneseTraditional unit (still used in some regions)

300 tsubo (about 991.74 m²), about a quarter of an acre. A traditional measure of farmland.

Rice paddies were counted in tan. One tan is 300 tsubo, or exactly 120,000/121 square metres, about 991.7, which is slightly less than a quarter of an acre. It equals ten se, and ten tan make a cho, so a farmer with several tan had a modest holding by the standards of the tax registers.

The unit belongs to the same system that valued land in koku of rice. Under the Tokugawa shogunate the kokudaka assessed a plot by its yield, and surveyed land was recorded in these agricultural areas. A common claim that one tan was the area needed to grow one koku is not confirmed by the sources consulted, so it should be taken as a rough tradition.

Japan signed the Metre Convention in 1885 and the 1891 weights and measures law gave the traditional units fixed metric equivalents. The Measurements Law of 1951 moved the country to metric units from 1959, and the tan survives mainly in rural land transactions and in talk of rice farming.

1 tan = 991.7355372 square meters (approximately).

Sources: Wikipedia: Japanese units of measurement; Wikipedia: Kokudaka; Wikipedia: Koku

Square Mile (mi²)

US & ImperialCurrent unit

640 acres or about 2.59 km². Used for the area of cities, states and countries in the US and UK.

A thousand Roman paces, mille passus, became the mile, and under Elizabeth I Parliament fixed the statute mile at eight furlongs, or 5,280 feet, in place of the older Roman-based value. The square mile inherits that length. Its most famous use came in the United States: the Land Ordinance of 1785 started the Public Land Survey System so that western land could be surveyed and sold to pay war debts, beginning with the Seven Ranges in eastern Ohio.

In that system a section is roughly one square mile, or 640 acres, and a township is 36 sections in a square six miles on a side. One square mile is nearly 2.59 million square meters. Chicago's Midway International Airport, at about 650 acres, covers roughly 1.02 square miles. Beware the phrase mile square: a region 20 miles square has 400 square miles, but so does a rectangle 10 by 40 miles. The US survey version of the mile was retired from 1 January 2023, but the international square mile remains the unit for cities, states and countries in the US and UK.

1 square mile = 2,589,988.11 square meters (approximately).

Sources: Wikipedia: Square mile; Wikipedia: Public Land Survey System; Wikipedia: Mile

Related conversions

See all area units.