Square mile

square mile
square mile
	Midway International Airport is about 650 acres (1.02 mi2) in area.
General information
Unit system	Imperial, United States customary units
Unit of	area
Symbol	mi2, sq mi
Conversions
1 mi2 in ...	... is equal to ...
Imperial/US	4.0145×109 sq in; 2.7878×107 ft2; 3.0976×106 yd2; 640 acres;
SI units	2589988.110336 m2; 2.589988110336 km2;

The square mile (abbreviated as sq mi and sometimes as mi²)^[2] is an imperial and US unit of measure for area. One square mile is equal to the area of a square with each side measuring a length of one mile.^[3]

Equivalents

One square mile is equal to:

about four billion square inches^[4]
nearly 27.9 million square feet
nearly 3.1 million square yards
2,560 roods
640 acres

One square mile is also equivalent to:

nearly 2.59 million square meters
nearly 25.9 billion square centimeters
nearly 2.59 trillion square millimeters

Similarly named units

Miles square

Square miles should not be confused with miles square, a square region with each side having a length of the value given. For example, a region which is 20 miles square (20 miles × 20 miles) has an area of 400 mi²; a rectangle of measuring 10 miles × 40 miles also has an area of 400 mi², but is not 20 miles square.

Section

In the United States Public Land Survey System, "square mile" is an informal synonym for section.

References

^ "FAA Airport Form 5010 for MDW" (PDF). FAA. . effective February 19, 2026.
^ Rowlett, Russ (September 1, 2004). "S", How Many? A Dictionary of Units of Measurement. University of North Carolina at Chapel Hill. Retrieved February 22, 2012.
^ Davies, Charles (1872). Mathematical dictionary and cyclopedia of mathematical science. Original from Harvard University: A.S. Barnes and co. p. 582.
^ François Cardarelli (2003). Encyclopaedia of scientific units, weights, and measures: their SI equivalences and origins. Springer. p. 3. ISBN 978-1-85233-682-0. Retrieved 22 February 2012.

Formula Conversion, Square miles to numerous area units with algebraic steps and unit cancellation shown

[FAA-1] "FAA Airport Form 5010 for MDW" (PDF). FAA. . effective February 19, 2026.

[RussRowlett-2] Rowlett, Russ (September 1, 2004). "S", How Many? A Dictionary of Units of Measurement. University of North Carolina at Chapel Hill. Retrieved February 22, 2012.

[Davies-3] Davies, Charles (1872). Mathematical dictionary and cyclopedia of mathematical science. Original from Harvard University: A.S. Barnes and co. p. 582.

[Cardarelli20032-4] François Cardarelli (2003). Encyclopaedia of scientific units, weights, and measures: their SI equivalences and origins. Springer. p. 3. ISBN 978-1-85233-682-0. Retrieved 22 February 2012.

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