Tan to Square Inches (tan to in²)

1 tan equals 1,537,193.157 square inches (rounded).

1 tan = 1,537,193.157 square inches

How to convert tan to square inches

To convert tan to square inches, multiply the number of tan by 1,537,193.157. The factor is rounded to 10 significant digits. To go the other way, multiply square inches by 6.505363333×10⁻⁷ (rounded).

square inches = tan × 1,537,193.157

Example: 10 tan = 15,371,931.57 square inches.

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 Inch (in²)

US & ImperialCurrent unit

A square one inch on a side, exactly 6.4516 cm². Used for small parts and for pressure (pounds per square inch).

Latin uncia, one twelfth, gave English the inch, which Old English borrowed as ynce. A statute of Edward II in 1324 defined it as three barleycorns, dry and round, set end to end, and the barleycorn remained the base for centuries after 1066. The modern square inch rests on a 20th-century agreement: the United States adopted a yard of exactly 0.9144 meter on 1 July 1959, the United Kingdom followed effective 1 January 1964, and the inch became exactly 25.4 mm.

Squaring that gives exactly 6.4516 cm² for one square inch, and one square meter is about 1,550 of them. Its best-known descendant is the pound per square inch, psi, the pressure unit still used for American tires and air tanks: atmospheric pressure at sea level is about 14.7 psi, a car tire is typically inflated to around 32 psi above the surrounding air, and one psi is about 6.895 kilopascals. The square inch itself is common in the US and UK for small parts and printed material.

1 square inch = 0.00064516 square meters (exactly).

Sources: Wikipedia: Square inch; Wikipedia: Inch; Wikipedia: Pounds per square inch

Related conversions

See all area units.