How many acres are in a square mile?
There are exactly 640 acres in one square mile.
Acres to Square Miles Calculator
Convert land area between acres and square miles in either direction.
Convert acres and square miles
Enter an area and choose the conversion direction.
About this converter
How to use Acres to Square Miles Calculator, plus the formulas and logic behind the results.
Tool description
Acres and square miles are US customary land units. A square mile is exactly 640 acres.
How to use
- Enter the area value.
- Choose the direction matching the unit you entered.
- Select Calculate to apply the conversion factor.
- Review the result in acres or square miles.
Formulas & reference
square miles = acres ÷ 640acres = square miles × 640
Calculation logic
The selected direction either divides by or multiplies by the exact factor 640.
Acres to Square Miles Calculator FAQ
Common questions about this conversion and how to interpret the result.
How many square miles is 100 acres?
100 acres is 0.15625 square miles.
Is a section of land one square mile?
In the US Public Land Survey System, a standard section is nominally one square mile or 640 acres.
Can the input contain decimals?
Yes. Fractional acres and square miles are supported.
Is this a linear conversion?
No. These are area units, but their direct area ratio is exactly 640 to 1.
Are nautical square miles used?
No. Square mile here means the statute square mile.