How many acres are equivalent to one square mile?

One square mile is equivalent to 640 acres because a square mile measures an area of one mile by one mile. To understand this in more detail, consider that a mile consists of 5,280 feet, so when you calculate the area of a square mile, you multiply the length of one side (5,280 feet) by the length of the other side (also 5,280 feet). This gives you 27,878,400 square feet in total for a square mile.

To convert square feet to acres, you use the conversion factor that one acre is 43,560 square feet. Dividing the total number of square feet in a square mile by the number of square feet in an acre results in:

27,878,400 square feet ÷ 43,560 square feet per acre = 640 acres.

This is why the conversion of one square mile to acres is 640, making it a fundamental understanding in land measurement, especially in fields like surveying and real estate.