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Convert square miles to acres

Please provide values below to convert square mile [mi^2] to acre [ac], or vice versa.


Square mile

Definition: The square mile (symbol: sq mi or mi2) is a unit of area in the imperial and United States customary (UCS) systems of units. It is defined as the area of a square with side lengths of one statute mile (5,280 feet). A square mile is a large area that is equal to 27,878,400 square feet, 3,097,600 square yards, and 640 acres.

History/origin: Area is commonly represented in the form of a square with sides of a specific unit of length, written as "square" followed by the chosen unit of length. The square mile is one of many such units and is derived from the area of a square with sides of one mile.

Current use: Square miles are used when the measurement involves large scales such as country sizes. It can be used when referencing population studies, such as a measurement of total population per square mile. As an imperial and USC unit, it is most commonly used in countries that use these systems of measurement. In countries that have adopted the International System of Units, the square meter (and its subsequent multiples and submultiples) is the preferred system of measurement.


Definition: An acre (symbol: ac) is a unit of land area used in the imperial and US customary systems. It is defined as the area of 1 chain (66 feet) by 1 furlong (660 feet), which is exactly equal to 1/640 of a square mile, 43,560 square feet, or exactly 4046.8564224 square meters.

History/origin: In the Middle Ages, the acre was defined as the area that a yoke (pair) of oxen could typically plow within one day, using a wooden plow. Before the metric system was adopted, many countries used their own versions of the acre. The most commonly used acre today, the international acre, is based on the international yard, which was defined in 1959.

Current use: Acres are used in countries including the United States, the UK, Ghana, India, Canada, and others. The United States (US) uses both international as well as US survey acres (~4047 square meters), which vary based on which type of yard is used in the measurement. However, area measurements are typically not accurate enough for the difference between the two acre measurements to be detectable.

Square Mile to Acre Conversion Table

Square Mile [mi^2]Acre [ac]
0.01 mi^26.4 ac
0.1 mi^264 ac
1 mi^2640 ac
2 mi^21280 ac
3 mi^21920 ac
5 mi^23200 ac
10 mi^26400 ac
20 mi^212800 ac
50 mi^232000 ac
100 mi^264000 ac
1000 mi^2640000 ac

How to Convert Square Mile to Acre

1 mi^2 = 640 ac
1 ac = 0.0015625 mi^2

Example: convert 15 mi^2 to ac:
15 mi^2 = 15 × 640 ac = 9600 ac

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