CALCULATOR
Acres to Square Miles Converter
Convert acres to square miles. For example, 2.5 ac equals 0.00390625 mi². Enter a nonnegative value up to 1,000,000,000 to update the result.
How the calculation works
Square Miles = Acres × (1/640).
Worked example
With acres 1 ac, square miles is 0.0015625 mi².
Assumptions and limits
International-acre basis43560international ft²; not historical US survey acre or jurisdictional land registry.