The square mile (abbreviated as sq mi and sometimes as mi2) is an imperial and US unit of measure for an area equal to the area of a square of one statute mile. It should not be confused with miles square, which refers to the number of miles on each side squared. For instance, 20 miles square (20 × 20 miles) is equal to 400 square miles; an area of 10 × 40 miles is likewise 400 square miles, but it is not 20 miles square.
One square mile is equivalent to:
- 4,014,489,600 square inches
- 27,878,400 square feet
- 3,097,600 square yards
- 640 acres
- 258.9988110336 hectares
- 2560 roods
- 25,899,881,103.36 square centimetres
- 2,589,988.110336 square metres
- 2.589988110336 square kilometres
When applied to a portion of the earth's surface, which is curved rather than flat, "square mile" is an informal synonym for section.
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