Square Miles to Acres Converter
One Square Mile equals 640 Acres (1 mi2 = 640 acre). Multiply a Square Mile value by 640 to get the equivalent in Acres. Enter a value above to calculate the result. You can also use the formula and reference table below.
Formula
acre = mi2 × 640
Multiply the Square Mile value by 640 to get the equivalent value in Acres.
Example Conversions
1 Square Mile (mi2)
640 Acre (acre)
5 Square Mile (mi2)
3200 Acre (acre)
10 Square Mile (mi2)
6400 Acre (acre)
25 Square Mile (mi2)
16000 Acre (acre)
100 Square Mile (mi2)
64000 Acre (acre)
Conversion Table
| Square Mile (mi2) | Acre (acre) |
|---|---|
| 0.1 | 64 |
| 0.5 | 320 |
| 1 | 640 |
| 2 | 1280 |
| 5 | 3200 |
| 10 | 6400 |
| 25 | 16000 |
| 50 | 32000 |
| 100 | 64000 |
| 250 | 160000 |
| 500 | 320000 |
| 1000 | 640000 |
How to Convert Manually
Use these steps to convert Square Mile values to Acre without the calculator.
- Write down the value in Square Mile (mi2) that you want to convert.
- Multiply that value by 640.
- For example, 10 Square Miles × 640 = 6400 Acres.
- Label the result as Acre (acre).
Relative Size Comparison
This chart shows the visual difference in size between exactly one Square Mile and one Acre.
About Square Mile and Acre
The square mile is 640 acres, about 2.59 square kilometers. US geography uses it for counties, cities, and large land areas. The acre is 43,560 square feet, exactly 4,046.8564224 square meters. Historically, it described the area a yoke of oxen could plow in a day. US and UK land sales still quote it. One Square Mile equals 640 Acres (1 mi2 = 640 acre). Square Mile is used in US city and county areas and in US population density figures. Acre is used in US and UK land sales.
Precision and Rounding:Area factors are the squares of exact length factors, so they are exact too (1 ft² = 0.09290304 m² precisely). Whole numbers usually suffice for rooms and land parcels; surveying and legal land descriptions carry four or more decimal places.
Conversion factors per NIST Special Publication 811 and the BIPM SI Brochure (9th edition) (reference).
Worked Example
15Square Miles equals9600Acres.
15 mi2 × 640 = 9600 acre
FAQ
How do I convert Square Mile to Acre?
Multiply the Square Mile value by 640 to get the equivalent value in Acres.
What is the formula for Square Mile to Acre?
The formula is acre = mi2 × 640.
How many Acres are in 1 Square Mile?
1 Square Mile equals 640 Acres.
Can I convert Acre back to Square Mile?
Yes. 1 Acre equals 0.0015625 Square Miles, and the related converter can reverse the calculation.
What are common names for Square Mile and Acre?
Square Mile is shown as mi2 and may also be searched as square miles, sq mi, mi². Acre is shown as acre and may also be searched as acres.
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