Square Chains to Square Miles (sq ch to mi²)
1 square chain equals 0.00015625 square miles exactly.
How to convert square chains to square miles
To convert square chains to square miles, multiply the number of square chains by 0.00015625. This factor is exact. To go the other way, multiply square miles by 6,400.
square miles = square chains × 0.00015625
Example: 10 square chains = 0.0015625 square miles.
About these units
Square Chain (sq ch)
484 square yards (404.69 m²), one tenth of an acre. A surveying unit.
Surveyors rather than farmers gave this unit its shape. In 1620 the English clergyman and mathematician Edmund Gunter devised a measuring chain of 100 links that was 66 feet long, and by 1675 it was in wide use. A square chain, 66 feet by 66 feet, covers 4,356 square feet, or 484 square yards. The convenient result is that ten of them make exactly one acre, so a plot measured in chains could be turned into acres by moving a decimal point.
That arithmetic was the reason the US adopted the chain. A report by Thomas Jefferson in 1784 led to the Land Ordinance of 1785, which required the chain for surveying the public lands, and many American property lines still trace back to chain measurements. In metric terms a square chain is about 404.69 square meters. The linear chain remains in niche use, for example in railway milepost distances in Britain, in wildfire spread rates in the United States, and as the length of a cricket pitch.
1 square chain = 404.6856422 square meters (approximately).
Sources: Wikipedia: Chain (unit); Wikipedia: Acre; Wikipedia: Rod (unit)
Square Mile (mi²)
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
- Square miles to square chains (reverse)
- Square chains to square meters
- Square chains to square kilometers
- Square chains to hectares
- Square chains to square inches
- Square chains to square feet
- Square chains to square yards
- Square chains to acres
- Square meters to square miles
- Square kilometers to square miles
- Hectares to square miles
- Square inches to square miles
- Square feet to square miles
- Square yards to square miles
- Acres to square miles
- Square centimeters to square miles
- Square millimeters to square miles
- Tsubo to square miles
- Pyeong to square miles
- Rai (Thai) to square miles
See all area units.