Acres to Square Miles Converter
Enter the area in acres below to convert it to square miles.
Convert Acres to Square Miles
Enter a value in acres (ac) to convert to square miles (mi²).
Acre to Square Mile Conversion Table
Table showing various acre measurements converted to square miles. Click any preset value or arrow to load it into the converter.
| Acres (ac) | Square Miles (mi²) |
|---|---|
| 1 ac | 0.0015625 mi² |
| 2 ac | 0.003125 mi² |
| 5 ac | 0.0078125 mi² |
| 10 ac | 0.015625 mi² |
| 15 ac | 0.0234375 mi² |
| 20 ac | 0.03125 mi² |
| 25 ac | 0.0390625 mi² |
| 30 ac | 0.046875 mi² |
| 50 ac | 0.078125 mi² |
| 75 ac | 0.1171875 mi² |
How to Convert Acres to Square Miles
To convert acres to square miles, multiply the area by the following conversion ratio: 0.0015625 square miles/acre.
Since one acre is equal to 0.0015625 square miles, you can use this simple formula to convert:
The area in square miles is equal to the area in acres multiplied by 0.0015625.
For example, here's how to convert 640 acres to square miles using the formula above.
How Many Square Miles Are in an Acre?
There are 0.0015625 square miles in an acre, which is why we use this value in the formula above.
Our acre to square mile calculator automatically converts your area measurements with full decimal and scientific precision across US customary, imperial, and SI metric standards.
Acres and square miles are both units used to measure area. Keep reading to learn more about each unit.
What Is an Acre?
An acre is a unit of area equal to 4,046.8564224 square meters (m²), the base unit for area. Imperial & US Customary land unit equal to 43,560 square feet. [1]
The acre is classified as a US customary and imperial unit of area. Acres can be abbreviated as ac; for example, 1 acre can be written as 1 ac.
When working with acres (ac) in formulas or technical specifications, always verify whether your target system uses SI metric, US customary, or British imperial standards.
In practice, acres (ac) are widely used across large-scale industrial, bulk, and macro-level area specifications within US customary and imperial workflows, engineering documentation, and technical data sheets.
What Is a Square Mile?
A square mile is a unit of area equal to 2,589,988.110336 square meters (m²), the base unit for area. Equal to 640 acres or 2.589988 km². [2]
The square mile is classified as a US customary and imperial unit of area. Square Miles can be abbreviated as mi²; for example, 1 square mile can be written as 1 mi².
When working with square miles (mi²) in formulas or technical specifications, always verify whether your target system uses SI metric, US customary, or British imperial standards.
In practice, square miles (mi²) are widely used across large-scale industrial, bulk, and macro-level area specifications within US customary and imperial workflows, engineering documentation, and technical data sheets.
When converting area between acres (ac) and square miles (mi²), keep full floating-point precision (1 ac = 0.0015625 mi²; 1 mi² = 640 ac) during intermediate calculations and round only the final square mile figure to match your instrument tolerance.
More Acre & Square Mile Conversions
Need to calculate in the opposite direction? Use our square miles to acres converter (mi² to ac) to switch your starting unit immediately. You can also explore related tools such as converting square kilometers to square miles, converting acres to hectares, or converting acres to square feet.
Convert from Acres
Frequently Asked Questions
References
- [1]NIST OWM StandardNIST OWM (SI Units — Length & Area)·Area Metrology Standard — Acres (ac) to Square Miles (mi²)
- [2]NIST HB 44 SpecificationNIST HB 44 (Acre, Hectare & Land Survey Tables)·Unit Specifications: Acre (ac) & Square Mile (mi²)
- [3]NIST SP 811 ReferenceNIST SP 811 (NIST SP 811 App. B.9 (Area))·Conversion Factors & Mathematical Basis (ac to mi²)