How to convert acres to square miles
mi² = ac × 0.0015625Because one square mile equals 640 acres, you can also divide: mi² = ac ÷ 640.
An acre is smaller than a square mile: it takes 640 acres to make one square mile.
Worked examples
- 1 acre1 ac × 0.0015625 = 0.0015625 mi²
- 5 acres5 ac × 0.0015625 = 0.0078125 mi²
- 10 acres10 ac × 0.0015625 = 0.015625 mi²
- 20 acres20 ac × 0.0015625 = 0.03125 mi²
- 100 acres100 ac × 0.0015625 = 0.15625 mi²
Acres to square miles conversion table
Values are calculated by the conversion engine and rounded to 8 significant figures.
| Acres (ac) | Square miles (mi²) |
|---|---|
| 0.1 ac | 0.00015625 mi² |
| 0.25 ac | 0.000390625 mi² |
| 0.5 ac | 0.00078125 mi² |
| 1 ac | 0.0015625 mi² |
| 2 ac | 0.003125 mi² |
| 3 ac | 0.0046875 mi² |
| 4 ac | 0.00625 mi² |
| 5 ac | 0.0078125 mi² |
| 6 ac | 0.009375 mi² |
| 7 ac | 0.0109375 mi² |
| 8 ac | 0.0125 mi² |
| 9 ac | 0.0140625 mi² |
| 10 ac | 0.015625 mi² |
| Acres (ac) | Square miles (mi²) |
|---|---|
| 12 ac | 0.01875 mi² |
| 15 ac | 0.0234375 mi² |
| 20 ac | 0.03125 mi² |
| 25 ac | 0.0390625 mi² |
| 30 ac | 0.046875 mi² |
| 40 ac | 0.0625 mi² |
| 50 ac | 0.078125 mi² |
| 75 ac | 0.1171875 mi² |
| 100 ac | 0.15625 mi² |
| 250 ac | 0.390625 mi² |
| 500 ac | 0.78125 mi² |
| 1,000 ac | 1.5625 mi² |
About the units
Acre (ac)
43,560 ft² (4,046.8564224 m²). Historically the land one ox team could plough in a day; still the US and UK unit for land parcels.
Square mile (mi²)
640 acres. Used for US counties, states and wildfire extents. One square mile equals 2,589,988.11 square meters (m²).
Frequently asked questions
How many square miles are in one acre?
There are 0.0015625 square miles in one acre, and this value is exact by definition.
How do I convert acres to square miles?
Multiply the number of acres by 0.0015625. For example, 10 ac × 0.0015625 = 0.015625 mi².
How many acres are in one square mile?
One square mile equals 640 acres. That is the reverse factor, 1 ÷ 0.0015625.
What is 10 acres in square miles?
10 ac = 0.015625 mi².
Is this ac to mi² converter accurate?
Yes. Both units are defined exactly in terms of SI units, so the conversion factor is exact; results are shown to 12 significant figures by default and you can change precision in the converter. Calculations run in your browser using the same tested engine that generated this page.