Square miles to acres (mi2 to ac) area units conversion factor is 640. To find out how many acres in square miles, multiply by the conversion factor or use the converter.
1 Square Mile = 640 Acres
There are 640 acres in a square mile, because an acre is defined as an area of 66 feet to 660 feet and equals to 66 * 660 = 43560 square feet and one mile is 5280 feet and one sq. mile equals to 5280 * 5280 = 27878400 square feet, that makes 27878400 / 43560 = 640 acres in a square mile.
For example, to find out how many acres there are in a square mile and a half, as a formula to convert from sq. miles to acres, multiply the sq. mile value by 640, that makes 1.5 mi2 * 640 = 960 acres in 1.5 sq. miles.
Square mile and acre are imperial and US customary area units and one square mile equals to 640 acres and 259 hectares. The abbreviations are "mi2" and "ac".