Acres to Square Miles
An acre is 4,840 square yards, roughly the size of a football field, the traditional unit for land area in the US and UK. A square mile is 640 acres, used to describe the area of cities, counties, and large regions in the US. 1 ac equals 0.0015625 mi², so converting between them is a matter of multiplying by that fixed factor — type any value into the converter below and both sides update instantly as you type.
Both units belong to area, measured here against area's base unit (m²) — every other area unit on this site converts through that same reference point, which is why the table below can also be read as a quick cross-check against nearby values.
Formula
mi² = ac × 0.0015625
ac = mi² × 640
Worked example: 5 ac × 0.0015625 = 0.0078125 mi².
Conversion table
| Acre (ac) | Square Mile (mi²) |
|---|---|
| 1 ac | 0.0015625 mi² |
| 2 ac | 0.003125 mi² |
| 3 ac | 0.0046875 mi² |
| 5 ac | 0.0078125 mi² |
| 10 ac | 0.015625 mi² |
| 20 ac | 0.03125 mi² |
| 25 ac | 0.0390625 mi² |
| 50 ac | 0.078125 mi² |
| 100 ac | 0.15625 mi² |
| 250 ac | 0.390625 mi² |
| 500 ac | 0.78125 mi² |
| 1,000 ac | 1.5625 mi² |
Frequently asked
- How many Square Miles in a acre?
- 1 ac equals 0.0015625 mi².
- How do I convert Acres to Square Miles?
- Multiply the value in ac by 0.0015625 to get mi². The converter above does this instantly as you type.
- Is the conversion exact?
- Yes — Acre and Square Mile are both defined by a fixed conversion factor to area's base unit (m²), so the result shown is exact to the precision displayed, not an approximation.